Ethereum-based customized software and networks, independent from the public Ethereum chain, are being tested by enterprise software companies.[48] Interested parties include Microsoft, IBM, JPMorgan Chase,[33][49] Deloitte,[50] R3,[51] Innovate UK (cross-border payments prototype).[52] Barclays, UBS and Credit Suisse are experimenting with Ethereum blockchain to automate Markets in Financial Instruments Directive (MiFID) II requirements.

The domain name "bitcoin.org" was registered on 18 August 2008.[17] On 31 October 2008, a link to a paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System[4] was posted to a cryptography mailing list.[18] Nakamoto implemented the bitcoin software as open-source code and released it in January 2009.[19][20][11] Nakamoto's identity remains unknown.[10]
The domain name "bitcoin.org" was registered on 18 August 2008.[17] On 31 October 2008, a link to a paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System[4] was posted to a cryptography mailing list.[18] Nakamoto implemented the bitcoin software as open-source code and released it in January 2009.[19][20][11] Nakamoto's identity remains unknown.[10]
Bloomberg reported that the largest 17 crypto merchant-processing services handled $69 million in June 2018, down from $411 million in September 2017. Bitcoin is "not actually usable" for retail transactions because of high costs and the inability to process chargebacks, according to Nicholas Weaver, a researcher quoted by Bloomberg. High price volatility and transaction fees make paying for small retail purchases with bitcoin impractical, according to economist Kim Grauer. However, bitcoin continues to be used for large-item purchases on sites such as Overstock.com, and for cross-border payments to freelancers and other vendors.[141]
Until relatively recently, building blockchain applications has required a complex background in coding, cryptography, mathematics as well as significant resources. But times have changed. Previously unimagined applications, from electronic voting & digitally recorded property assets to regulatory compliance & trading are now actively being developed and deployed faster than ever before. By providing developers with the tools to build decentralized applications, Ethereum is making all of this possible.
In 2014, researchers at the University of Kentucky found "robust evidence that computer programming enthusiasts and illegal activity drive interest in bitcoin, and find limited or no support for political and investment motives".[134] Australian researchers have estimated that 25% of all bitcoin users and 44% of all bitcoin transactions are associated with illegal activity as of April 2017. There were an estimated 24 million bitcoin users primarily using bitcoin for illegal activity. They held $8 billion worth of bitcoin, and made 36 million transactions valued at $72 billion.[225][226]
بيتكوين (بالإنجليزية: Bitcoin) هي عملة معماة ونظام دفع عالمي يمكن مقارنتها بالعملات الأخرى مثل الدولار أو اليورو، لكن مع عدة فوارق أساسية، من أبرزها أن هذه العملة هي عملة إلكترونية بشكل كامل تتداول عبر الإنترنت فقط من دون وجود فيزيائي لها.[1] وهي أول عملة رقمية لامركزية - فهي نظام يعمل دون مستودع مركزي أو مدير واحد، أي أنها تختلف عن العملات التقليدية بعدم وجود هيئة تنظيمية مركزية تقف خلفها. وتتم المعاملات بشبكة الند للند بين المستخدمين مباشرة دون وسيط من خلال استخدام التشفير. يتم التحقق من هذه المعاملات عن طريق عُقد الشبكة وتسجيلها في دفتر حسابات موزع وعام يسمى سلسلة الكتل. اخترع البيتكوين شخص غير معروف أو مجموعة من الناس عرف باسم ساتوشي ناكاموتو وأُصدِر كبرنامج مفتوح المصدر في عام 2009.

The use of bitcoin by criminals has attracted the attention of financial regulators, legislative bodies, law enforcement, and the media.[218] In the United States, the FBI prepared an intelligence assessment,[219] the SEC issued a pointed warning about investment schemes using virtual currencies,[218] and the U.S. Senate held a hearing on virtual currencies in November 2013.[220] The U.S. government claimed that bitcoin was used to facilitate payments related to Russian interference in the 2016 United States elections.[221]
The price of bitcoins has gone through cycles of appreciation and depreciation referred to by some as bubbles and busts.[159] In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2.[160] In the latter half of 2012 and during the 2012–13 Cypriot financial crisis, the bitcoin price began to rise,[161] reaching a high of US$266 on 10 April 2013, before crashing to around US$50. On 29 November 2013, the cost of one bitcoin rose to a peak of US$1,242.[162] In 2014, the price fell sharply, and as of April remained depressed at little more than half 2013 prices. As of August 2014 it was under US$600.[163] During their time as bitcoin developers, Gavin Andresen[164] and Mike Hearn[165] warned that bubbles may occur.
Leveraged trading in foreign currency or off-exchange products on margin carries significant risk and may not be suitable for all investors. We advise you to carefully consider whether trading is appropriate for you based on your personal circumstances. Forex trading involves risk. Losses can exceed deposits. We recommend that you seek independent advice and ensure you fully understand the risks involved before trading.

Though transaction fees are optional, miners can choose which transactions to process and prioritize those that pay higher fees.[77] Miners may choose transactions based on the fee paid relative to their storage size, not the absolute amount of money paid as a fee. These fees are generally measured in satoshis per byte (sat/b). The size of transactions is dependent on the number of inputs used to create the transaction, and the number of outputs.[7]:ch. 8
On 3 January 2009, the bitcoin network was created when Nakamoto mined the first block of the chain, known as the genesis block.[21][22] Embedded in the coinbase of this block was the text "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks".[11] This note references a headline published by The Times and has been interpreted as both a timestamp and a comment on the instability caused by fractional-reserve banking.[23]:18
Ethereum blockchain applications are usually referred to as DApps (decentralized application), since they are based on the decentralized Ethereum Virtual Machine, and its smart contracts.[46] Many uses have been proposed for Ethereum platform, including ones that are impossible or unfeasible.[47][33] Use case proposals have included finance, the internet-of-things, farm-to-table produce, electricity sourcing and pricing, and sports betting. Ethereum is (as of 2017) the leading blockchain platform for initial coin offering projects, with over 50% market share.
The price of bitcoins has gone through cycles of appreciation and depreciation referred to by some as bubbles and busts.[159] In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2.[160] In the latter half of 2012 and during the 2012–13 Cypriot financial crisis, the bitcoin price began to rise,[161] reaching a high of US$266 on 10 April 2013, before crashing to around US$50. On 29 November 2013, the cost of one bitcoin rose to a peak of US$1,242.[162] In 2014, the price fell sharply, and as of April remained depressed at little more than half 2013 prices. As of August 2014 it was under US$600.[163] During their time as bitcoin developers, Gavin Andresen[164] and Mike Hearn[165] warned that bubbles may occur.
The unit of account of the bitcoin system is a bitcoin. Ticker symbols used to represent bitcoin are BTC[a] and XBT.[b][72]:2 Its Unicode character is ₿.[1] Small amounts of bitcoin used as alternative units are millibitcoin (mBTC), and satoshi (sat). Named in homage to bitcoin's creator, a satoshi is the smallest amount within bitcoin representing 0.00000001 bitcoins, one hundred millionth of a bitcoin.[2] A millibitcoin equals 0.001 bitcoins; one thousandth of a bitcoin or 100,000 satoshis.[73]
Smart contract is just a phrase used to describe a computer code that can facilitate the exchange of money, content, property, shares, or anything of value. When running on the blockchain a smart contract becomes like a self-operating computer program that automatically executes when specific conditions are met. Because smart contracts run on the blockchain, they run exactly as programmed without any possibility of censorship, downtime, fraud or third-party interference.
The first wallet program, simply named Bitcoin, and sometimes referred to as the Satoshi client, was released in 2009 by Satoshi Nakamoto as open-source software.[11] In version 0.5 the client moved from the wxWidgets user interface toolkit to Qt, and the whole bundle was referred to as Bitcoin-Qt.[107] After the release of version 0.9, the software bundle was renamed Bitcoin Core to distinguish itself from the underlying network.[108][109]
بيتكوين (بالإنجليزية: Bitcoin) هي عملة معماة ونظام دفع عالمي يمكن مقارنتها بالعملات الأخرى مثل الدولار أو اليورو، لكن مع عدة فوارق أساسية، من أبرزها أن هذه العملة هي عملة إلكترونية بشكل كامل تتداول عبر الإنترنت فقط من دون وجود فيزيائي لها.[1] وهي أول عملة رقمية لامركزية - فهي نظام يعمل دون مستودع مركزي أو مدير واحد، أي أنها تختلف عن العملات التقليدية بعدم وجود هيئة تنظيمية مركزية تقف خلفها. وتتم المعاملات بشبكة الند للند بين المستخدمين مباشرة دون وسيط من خلال استخدام التشفير. يتم التحقق من هذه المعاملات عن طريق عُقد الشبكة وتسجيلها في دفتر حسابات موزع وعام يسمى سلسلة الكتل. اخترع البيتكوين شخص غير معروف أو مجموعة من الناس عرف باسم ساتوشي ناكاموتو وأُصدِر كبرنامج مفتوح المصدر في عام 2009.
There are many ways you can plug into the Ethereum network, one of the easiest ways is to use its native Mist browser. Mist provides a user-friendly interface & digital wallet for users to trade & store Ether as well as write, manage, deploy and use smart contracts. Like web browsers give access and help people navigate the internet, Mist provides a portal into the world of decentralized blockchain applications.

Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[95] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[7]:ch. 1 Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
Ethereum was proposed in late 2013 by Vitalik Buterin, a cryptocurrency researcher and programmer. Development was funded by an online crowdsale that took place between July and August 2014.[4] The system then went live on 30 July 2015, with 72 million coins "premined". This accounts for about 68 percent of the total circulating supply in 2019. [5]
In October 2015,[63] a development governance was proposed as Ethereum Improvement Proposal, aka EIP, standardized on EIP-1.[64] The core development group and community were to gain consensus by a process regulated EIP. A few notable decisions were made in the process of EIP, such as EIP-160 (EXP cost increase caused by Spurious Dragon Hardfork)[65] and EIP-20 (ERC-20 Token Standard).[66] In January 2018, the EIP process was finalized and published as EIP-1 status turned "active".[63]

Third-party internet services called online wallets offer similar functionality but may be easier to use. In this case, credentials to access funds are stored with the online wallet provider rather than on the user's hardware.[97] As a result, the user must have complete trust in the online wallet provider. A malicious provider or a breach in server security may cause entrusted bitcoins to be stolen. An example of such a security breach occurred with Mt. Gox in 2011.[98]
Izabella Kaminska, the editor of FT Alphaville, has pointed out that criminals are using Ethereum to run Ponzi schemes and other forms of investment fraud.[67] The article was based on a paper from the University of Cagliari, which placed the number of Ethereum smart contracts which facilitate Ponzi schemes at nearly 10% of 1384 smart contracts examined. However, it also estimated that only 0.05% of the transactions on the network were related to such contracts.[68]
Ethereum enables developers to build and deploy decentralized applications. A decentralized application or Dapp serve some particular purpose to its users. Bitcoin, for example, is a Dapp that provides its users with a peer to peer electronic cash system that enables online Bitcoin payments. Because decentralized applications are made up of code that runs on a blockchain network, they are not controlled by any individual or central entity.
Like Bitcoin, Ethereum is a distributed public blockchain network. Although there are some significant technical differences between the two, the most important distinction to note is that Bitcoin and Ethereum differ substantially in purpose and capability. Bitcoin offers one particular application of blockchain technology, a peer to peer electronic cash system that enables online Bitcoin payments. While the Bitcoin blockchain is used to track ownership of digital currency (bitcoins), the Ethereum blockchain focuses on running the programming code of any decentralized application.
We are always looking for feedback on the platform and user suggestions are regularly included in future releases of this price tracking software. The website is currently undergoing development to include price data from all ERC20 tokens as well order book data, blockchain usage data and more. We endeavour to keep the site simple to use with clear data visualizations that help investors stay abreast of the latest Ethereum price movements. We are determined to keep this webapp free from intrusive advertising; please share this website and its content!
Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[95] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[7]:ch. 1 Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices.
Network nodes can validate transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes. To achieve independent verification of the chain of ownership each network node stores its own copy of the blockchain.[76] About every 10 minutes, a new group of accepted transactions, called a block, is created, added to the blockchain, and quickly published to all nodes, without requiring central oversight. This allows bitcoin software to determine when a particular bitcoin was spent, which is needed to prevent double-spending. A conventional ledger records the transfers of actual bills or promissory notes that exist apart from it, but the blockchain is the only place that bitcoins can be said to exist in the form of unspent outputs of transactions.[7]:ch. 5
Full clients verify transactions directly by downloading a full copy of the blockchain (over 150 GB As of January 2018).[95] They are the most secure and reliable way of using the network, as trust in external parties is not required. Full clients check the validity of mined blocks, preventing them from transacting on a chain that breaks or alters network rules.[7]:ch. 1 Because of its size and complexity, downloading and verifying the entire blockchain is not suitable for all computing devices. 

بروتوكول التوجيه بين البوابات (BGP)   بروتوكول التهيئة الآليّة للمضيفين (DHCP) بروتوكول التطبيقات المقيدة (CoAP) نظام أسماء النطاقات (DNS) بروتوكول نقل النصّ الفائق (HTTP) بروتوكول الوصول إلى رسائل الإنترنت (IMAP) بروتوكول النفاذ إلى الدليل البسيط (LDAP) برتوكول نقل أخبار الشبكة (NNTP) بروتوكول التوقيت في الشبكة (NTP) بروتوكول مكتب البريد (POP) بروتوكول معلومات التوجيه (RIP) بروتوكول التدفق في الزمن حقيقي (RTSP) بروتوكول وصف الجلسة (SDP) بروتوكول بدء جلسة (SIP) بروتوكول نقل الملفات (FTP) بروتوكول نقل الملفات البسيط (TFTP) بروتوكول إرسال البريد البسيط (SMTP) بروتوكول إدارة الشبكات البسيط (SNMP) بروتوكول الاتصال الآمن (SSH) بروتوكول تل نت (Telnet) سبيدي (SPDY) مزيد ..
The receiver of the first bitcoin transaction was cypherpunk Hal Finney, who created the first reusable proof-of-work system (RPoW) in 2004.[24] Finney downloaded the bitcoin software on its release date, and on 12 January 2009 received ten bitcoins from Nakamoto.[25][26] Other early cypherpunk supporters were creators of bitcoin predecessors: Wei Dai, creator of b-money, and Nick Szabo, creator of bit gold.[21] In 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for ₿10,000.[27]

As the industry continues to investigate blockchain platforms, it’s apparent that Ethereum is becoming a de facto leader. For example, a few days ago JPMorgan publicly open-sourced its Quorum platform, architected and developed around the Go Ethereum client by Jeff Wilcke and his team. Several other major banks are using Ethereum, and Microsoft is anchoring its Bletchley platform on it as the foundational blockchain element. Industry, both publicly and confidentially, continues to contribute to Ethereum and work with us and others to help our promising, toddler-age codebase reach maturity. Stay tuned for news on this front.
تسمح تطبيقات بيتكوين والتي يُطلق عليها أحيانا اسم عميل بيتكوين للمُستخدمين بالتعامل مع شبكة بيتكوين. في شكله القاعدي يسمح التطبيق بتوليد وحفظ مفاتيح خاصة بالمُستخدم والاتصال بشبكة الند للند الخاص بالعُملة. تم إطلاق أول تطبيق بيتكوين سنة 2009 من طرف ساتوشي ناكاموتو مُؤسس عُملة بيتكوين كتطبيق مجاني ومفتوح المصدر. يُستخدم هذا التطبيق -والذي يُطلق عليه عادة اسم تطبيق ساتوشي- كمحفظة على الحواسيب الشخصية للقيام بعمليات دفع إلكترونية أو كخادوم لاستقبال تلك المدفوعات ولخدمات أخرى مُتعلقة بالدفع. أما تطبيق Bitcoin-Qt فيتم اعتباره كتطبيق مرجعي بحكم أنه يُمثل الآلية التي يعمل من خلالها بروتوكول بيتكوين ويُعتبر مثالا يُحتذى به لغيره من التطبيقات. لدى القيام بعمليات شراء باستخدام الهواتف الذكية فإنه عادة ما يتم استخدام تطبيقات بيتكوين تقوم بتوليد و/أو قراءة QR codes لتسهيل مهمة التحويل والدفع. كما تتوفر حاليا عدة تطبيقات تعمل كخواديم تقوم بتأكيد الإجراءات التي تتم على الشبكة وتقوم بإضافتها كتلة تحويلات.
Ethereum addresses are composed of the prefix "0x", a common identifier for hexadecimal, concatenated with the rightmost 20 bytes of the Keccak-256 hash (big endian) of the ECDSA public key (the curve used is the so called secp256k1, the same as Bitcoin). In hexadecimal, 2 digits represents a byte, meaning addresses contain 40 hexadecimal digits. An example of an Ethereum address is 0xb794F5eA0ba39494cE839613fffBA74279579268. Contract addresses are in the same format, however they are determined by sender and creation transaction nonce.[34] User accounts are indistinguishable from contract accounts given only an address for each and no blockchain data. Any valid Keccak-256 hash put into the described format is valid, even if it does not correspond to an account with a private key or a contract. This is unlike Bitcoin, which uses base58check to ensure that addresses are properly typed.
“A DAO consists of one or more contracts and could be funded by a group of like-minded individuals. A DAO operates completely transparently and completely independently of any human intervention, including its original creators. A DAO will stay on the network as long as it covers its survival costs and provides a useful service to its customer base” Stephen Tual, Slock.it Founder, former CCO Ethereum.

In March 2017, various blockchain start-ups, research groups, and Fortune 500 companies announced the creation of the Enterprise Ethereum Alliance (EEA) with 30 founding members.[16] By May, the nonprofit organization had 116 enterprise members—including ConsenSys, CME Group, Cornell University's research group, Toyota Research Institute, Samsung SDS, Microsoft, Intel, J. P. Morgan, Cooley LLP, Merck KGaA, DTCC, Deloitte, Accenture, Banco Santander, BNY Mellon, ING, and National Bank of Canada.[17][18][19] By July 2017, there were over 150 members in the alliance, including recent additions MasterCard, Cisco Systems, Sberbank and Scotiabank.[20][21]

تُعتبر بيتكوين عُملة معمّاة (بالإنجليزية: cryptocurrency) ويُقصد بذلك أنها تعتمد بشكل أساسي على مبادئ التشفير في جميع جوانبها، كما أنها تُعتبر أيضا العُملة الأولى من نوعها والأكثر شهرة وانتشارًا لكن رغم ذلك ليست العُملة التشفيرية الوحيدة الموجودة على شبكة الإنترنت حاليًا. حيث يتوفر ما يزيد عن 60 عُملة تشفيرية مُختلفة[6] منها 6 عُملات يُمكن وصفها بالرئيسية [7] وذلك اعتمادًا على عدد المُستخدمين وبنية كل شبكة، إضافة إلى الأماكن التي يُمكن استبدال وشراء هذه العُملات التشفيرية مُقابل عُملات أخرى. جميع العُملات التشفيرية الحالية مبنية على مبدأ عمل عُملة بيتكوين نفسها باستثناء عُملة Ripple [8]، وبما أن عُملة بيتكوين مفتوحة المصدر فإنه من المُمكن استنساخها وإدخال بعض التعديلات عليها ومن ثم إطلاق عُملة جديدة.
EthereumPrice.org was developed by Ether0x in March 2016 to allow users to easily track the price of Ethereum both historically and in real-time. The platform has since evolved to include several fiat currencies (EUR, GBP, JPY and others) as well as price data for a number of Ethereum ERC20 tokens and other blockchain currencies. More recently, prediction data from Augur was also added to provide insight into the future price expectations of the Ether market. Price data is currently sourced from multiple exchanges with the weighted average price of these assets being calculated by CryptoCompare.com. For more details on the weighted average calculation, see our FAQ.
تُعتبر بيتكوين عُملة معمّاة (بالإنجليزية: cryptocurrency) ويُقصد بذلك أنها تعتمد بشكل أساسي على مبادئ التشفير في جميع جوانبها، كما أنها تُعتبر أيضا العُملة الأولى من نوعها والأكثر شهرة وانتشارًا لكن رغم ذلك ليست العُملة التشفيرية الوحيدة الموجودة على شبكة الإنترنت حاليًا. حيث يتوفر ما يزيد عن 60 عُملة تشفيرية مُختلفة[6] منها 6 عُملات يُمكن وصفها بالرئيسية [7] وذلك اعتمادًا على عدد المُستخدمين وبنية كل شبكة، إضافة إلى الأماكن التي يُمكن استبدال وشراء هذه العُملات التشفيرية مُقابل عُملات أخرى. جميع العُملات التشفيرية الحالية مبنية على مبدأ عمل عُملة بيتكوين نفسها باستثناء عُملة Ripple [8]، وبما أن عُملة بيتكوين مفتوحة المصدر فإنه من المُمكن استنساخها وإدخال بعض التعديلات عليها ومن ثم إطلاق عُملة جديدة.
Bitcoin has been criticized for the amount of electricity consumed by mining. As of 2015, The Economist estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year).[136] At the end of 2017, the global bitcoin mining activity was estimated to consume between one and four gigawatts of electricity.[203] Politico noted that the even high-end estimates of bitcoin's total consumption levels amount to only about 6% of the total power consumed by the global banking sector, and even if bitcoin's consumption levels increased 100 fold from today's levels, bitcoin's consumption would still only amount to about 2% of global power consumption.[204]

If the private key is lost, the bitcoin network will not recognize any other evidence of ownership;[32] the coins are then unusable, and effectively lost. For example, in 2013 one user claimed to have lost 7,500 bitcoins, worth $7.5 million at the time, when he accidentally discarded a hard drive containing his private key.[78] About 20% of all bitcoins are believed to be lost. They would have a market value of about $20 billion at July 2018 prices.[79]
Physical wallets store the credentials necessary to spend bitcoins offline and can be as simple as a paper printout of the private key;[7]:ch. 10 a paper wallet. A paper wallet is created with a keypair generated on a computer with no internet connection; the private key is written or printed onto the paper[g] and then erased from the computer. The paper wallet can then be stored in a safe physical location for later retrieval. Bitcoins stored using a paper wallet are said to be in cold storage.[99]:39 In a 2014 interview, QuadrigaCX founder Gerald Cotten explained that the company stored customer funds on paper wallets in safe deposit boxes: "So we just send money to them, we don’t need to go back to the bank every time we want to put money into it. We just send money from our Bitcoin app directly to those paper wallets, and keep it safe that way."[100]

تتمتع عملة البيتكوين بقدر عالٍ من السرية. مبدئيا الأمر صحيح، حيث أن كل ما تحتاجه لإرسال بعض البيتكوينات لشخص آخر هو عنوانه فقط. لكن بحكم أنه يتم تسجيل كل عملية تحويل في سجل بيتكوين فإنه بالرغم من عدم معرفتك لهوية مالك أي عُنوان إلا أنه بمقدورك أن تعرف كم عدد البيتكوينات التي في حوزته وما هي العناوين التي أرسلت بيتكوينات إليه. إن قام أحدهم بالإعلان صراحة عن امتلاكه لعناوين بيتكوين مُعينة فإنه سيُصبح بإمكانك معرفة ما هي العناوين التي قامت بإرسال بيتكوينات إليه وما هي العناوين التي أرسل إليها بيتكوينات. الكشف عن عنوان البيتكوين الخاص بك ليس مُستبعدا، حيث أنك ستحتاج إلى إعطائه لغيرك في حال ما إذا احتجت أن يرسلوا لك بعض المال إليه. يُنصح باستخدام عناوين مُختلفة لعمليات تحويل مُختلفة للحفاظ على مُستوى مُعين من المجهولية، رغم ذلك هناك الكثيرون ممن لا يقومون بذلك. من الناحية التقنية يبقى تتبع مصدر بعض العمليات المشبوهة على شبكة بيتكوين مُمكنا، حيث يكفي تتبع عمليات التحويل إلى غاية وصولها إلى عنوان معروفة هوية صاحبه، وحينها يكفي القيام بعمليات تحقيق عكسية إلى غاية الوصول إلى صاحب الحساب المشبوه. صحيح بأن كم البيانات المُتعلقة بجميع عمليات التحويل ضخم، إلا أن قوة الحواسيب في تزايد مُستمر وإمكانية تتبع هذه العمليات واردة جدا، بل ويُمكن الجزم بأنه تتبع عمليات سرقة البيتكوينات أسهل بكثير من تتبع سرقة الأموال على هيئتها الورقية.


David Golumbia says that the ideas influencing bitcoin advocates emerge from right-wing extremist movements such as the Liberty Lobby and the John Birch Society and their anti-Central Bank rhetoric, or, more recently, Ron Paul and Tea Party-style libertarianism.[132] Steve Bannon, who owns a "good stake" in bitcoin, considers it to be "disruptive populism. It takes control back from central authorities. It's revolutionary."[133]
Third-party internet services called online wallets offer similar functionality but may be easier to use. In this case, credentials to access funds are stored with the online wallet provider rather than on the user's hardware.[97] As a result, the user must have complete trust in the online wallet provider. A malicious provider or a breach in server security may cause entrusted bitcoins to be stolen. An example of such a security breach occurred with Mt. Gox in 2011.[98]

Network nodes can validate transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes. To achieve independent verification of the chain of ownership each network node stores its own copy of the blockchain.[76] About every 10 minutes, a new group of accepted transactions, called a block, is created, added to the blockchain, and quickly published to all nodes, without requiring central oversight. This allows bitcoin software to determine when a particular bitcoin was spent, which is needed to prevent double-spending. A conventional ledger records the transfers of actual bills or promissory notes that exist apart from it, but the blockchain is the only place that bitcoins can be said to exist in the form of unspent outputs of transactions.[7]:ch. 5
Various journalists,[205][210] economists,[211][212] and the central bank of Estonia[213] have voiced concerns that bitcoin is a Ponzi scheme. In April 2013, Eric Posner, a law professor at the University of Chicago, stated that "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective delusion."[214] A July 2014 report by the World Bank concluded that bitcoin was not a deliberate Ponzi scheme.[215]:7 In June 2014, the Swiss Federal Council[216]:21 examined the concerns that bitcoin might be a pyramid scheme; it concluded that, "Since in the case of bitcoin the typical promises of profits are lacking, it cannot be assumed that bitcoin is a pyramid scheme." In July 2017, billionaire Howard Marks referred to bitcoin as a pyramid scheme.[217]
This dramatic volatility attracted global attention with the mainstream media running near-daily reports on the price of Ether. The publicity generated has been a major boon for the ecosystem, attracting thousands of new developers and business ventures alike. In 2018 the amount raised through Ethereum-enabled ICOs reached almost $8bn, increasing from just $90m in 2016. While the price of Ethereum has faced extreme volatility over the years, it is this volatility which has driven interest. After every boom and bust cycle, Ethereum comes out the other side with a fundamentally stronger platform and a broader developer community backing it. These fundamental improvements would suggest a positive long-term outlook on the price of Ethereum.
While it’s still early days, Mist, MetaMask and a variety of other browsers look set to make blockchain-based applications accessible to more people than ever before. Even people without a technical background can now potentially build blockchain apps. This is a revolutionary leap for blockchain technology that could bring decentralized applications into the mainstream.
Ethereum was proposed in late 2013 by Vitalik Buterin, a cryptocurrency researcher and programmer. Development was funded by an online crowdsale that took place between July and August 2014.[4] The system then went live on 30 July 2015, with 72 million coins "premined". This accounts for about 68 percent of the total circulating supply in 2019. [5]
Bitcoin has been criticized for the amount of electricity consumed by mining. As of 2015, The Economist estimated that even if all miners used modern facilities, the combined electricity consumption would be 166.7 megawatts (1.46 terawatt-hours per year).[136] At the end of 2017, the global bitcoin mining activity was estimated to consume between one and four gigawatts of electricity.[203] Politico noted that the even high-end estimates of bitcoin's total consumption levels amount to only about 6% of the total power consumed by the global banking sector, and even if bitcoin's consumption levels increased 100 fold from today's levels, bitcoin's consumption would still only amount to about 2% of global power consumption.[204]
Ethereum-based customized software and networks, independent from the public Ethereum chain, are being tested by enterprise software companies.[48] Interested parties include Microsoft, IBM, JPMorgan Chase,[33][49] Deloitte,[50] R3,[51] Innovate UK (cross-border payments prototype).[52] Barclays, UBS and Credit Suisse are experimenting with Ethereum blockchain to automate Markets in Financial Instruments Directive (MiFID) II requirements.
• عدم الإعتراف بها من قبل الجهات المُختصة: إستناداً إلى قول الإمام ابن تيمية: ’’الدراهم والدنانير لا تقصد لنفسها بل هي وسيلة إلى التعامل بها، ولهذا كانت أثمانا بخلاف سائر الأموال، فإن – هذه الاموال – المقصود الإنتفاع بها نفسها”. وفي وقتنا الحالى لا تعتمد تداول وإستثمار العُملات إلا بموجب إعتراف وموافقة من قبل الجهات المُختصة وعلى رأسها البنوك المركزية. وبحسب ما قُيل من قبل البنوك المركزية إنه لم يتم الإعتراف بعد بعُملات البيتكوين الإفتراضية كعٌملات صالحة للتداول والإستثمار. وطبقاً لذلك تُحرم عمليات التداول والإستثمار للبيتكوين.
Venture capitalists, such as Peter Thiel's Founders Fund, which invested US$3 million in BitPay, do not purchase bitcoins themselves, but instead fund bitcoin infrastructure that provides payment systems to merchants, exchanges, wallet services, etc.[154] In 2012, an incubator for bitcoin-focused start-ups was founded by Adam Draper, with financing help from his father, venture capitalist Tim Draper, one of the largest bitcoin holders after winning an auction of 30,000 bitcoins,[155] at the time called "mystery buyer".[156] The company's goal is to fund 100 bitcoin businesses within 2–3 years with $10,000 to $20,000 for a 6% stake.[155] Investors also invest in bitcoin mining.[157] According to a 2015 study by Paolo Tasca, bitcoin startups raised almost $1 billion in three years (Q1 2012 – Q1 2015).[158]
Ethereum addresses are composed of the prefix "0x", a common identifier for hexadecimal, concatenated with the rightmost 20 bytes of the Keccak-256 hash (big endian) of the ECDSA public key (the curve used is the so called secp256k1, the same as Bitcoin). In hexadecimal, 2 digits represents a byte, meaning addresses contain 40 hexadecimal digits. An example of an Ethereum address is 0xb794F5eA0ba39494cE839613fffBA74279579268. Contract addresses are in the same format, however they are determined by sender and creation transaction nonce.[34] User accounts are indistinguishable from contract accounts given only an address for each and no blockchain data. Any valid Keccak-256 hash put into the described format is valid, even if it does not correspond to an account with a private key or a contract. This is unlike Bitcoin, which uses base58check to ensure that addresses are properly typed.
Ether is a token whose blockchain is generated by the Ethereum platform. Ether can be transferred between accounts and used to compensate participant mining nodes for computations performed.[3] Ethereum provides a decentralized virtual machine, the Ethereum Virtual Machine (EVM), which can execute scripts using an international network of public nodes.[4] The virtual machine's instruction set, in contrast to others like Bitcoin Script, is thought to be Turing-complete. "Gas", an internal transaction pricing mechanism, is used to mitigate spam and allocate resources on the network.[4] 

^ Jump up to: a b c d e Joshua A. Kroll; Ian C. Davey; Edward W. Felten (11–12 June 2013). "The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries" (PDF). The Twelfth Workshop on the Economics of Information Security (WEIS 2013). Archived (PDF) from the original on 9 May 2016. Retrieved 26 April 2016. A transaction fee is like a tip or gratuity left for the miner.
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