طرح شخص أطلق على نفسه الاسم الرمزي ساتوشي ناكاموتو فكرة بيتكوين للمرة الأولى في ورقة بحثية في عام 2008،[2] ووصفها بأنها نظام نقدي إلكتروني يعتمد في التعاملات المالية على مبدأ الند للند (بالإنجليزية: Peer-to-Peer) ، وهو مصطلح تقني يعني التعامل المباشر بين مستخدم وآخر دون وجود وسيط (كالتورنت). يقول القائمون على بيتكوين إن الهدف من هذه العملة التي طرحت للتداول للمرة الأولى سنة 2009 [3] هو تغيير الاقتصاد العالمي بنفس الطريقة التي غيرت بها الويب أساليب النشر.[4] وفي عام 2016 أعلن رجل الأعمال الأسترالي كريغ رايت أنه هو ساتوشي ناكاموتو مقدما دليلا تقنيا على ذلك ولكن تم كشف زيف أدلّته بسهولة.[5]
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]
To be accepted by the rest of the network, a new block must contain a proof-of-work (PoW).[75] The system used is based on Adam Back's 1997 anti-spam scheme, Hashcash.[85][4] The PoW requires miners to find a number called a nonce, such that when the block content is hashed along with the nonce, the result is numerically smaller than the network's difficulty target.[7]:ch. 8 This proof is easy for any node in the network to verify, but extremely time-consuming to generate, as for a secure cryptographic hash, miners must try many different nonce values (usually the sequence of tested values is the ascending natural numbers: 0, 1, 2, 3, ...[7]:ch. 8) before meeting the difficulty target.
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]
• لا حرج من دفع عمولات تحويل العملات: كما هو شائع بالنسبة للبعض أن دفع العُمولات عبر شبكات الإنترنت مقابل خدمات تحويل أو شراء عُملات البيتكوين يُعد شكل من أشكال الربا غير المسموح بها. لكن إستناداُ إلى ما تم ذكره بحسب الفتوى رقم 259576 أن لا هناك أى حرج على دفع مثل هذه العمولات. حيث إنك تدفع مُقابل حصولك على خدمة معينة بما فيها خدمات تحويل وشراء عُملات البيتكوين الإفتراضية.

According to the European Central Bank, the decentralization of money offered by bitcoin has its theoretical roots in the Austrian school of economics, especially with Friedrich von Hayek in his book Denationalisation of Money: The Argument Refined,[127] in which Hayek advocates a complete free market in the production, distribution and management of money to end the monopoly of central banks.[128]:22
لنفرض بأن أغلب المُنقبين يستخدمون أجهزة تقارب في كفاءتها Radeon 5870 video card والتي يتم اعتبارها كإحدى أعلى البطاقات مردودية على هذا الموقع. بإمكان بطاقة Radeon 5870 أن تُنفذ 402 ميجا هاش في الثانية وتُكلف حوالي 1.2 دولار لليوم الواحد إن تم استخدامها على جهاز يحتوي بطاقتين من نفس النوع في الولايات المُتحدة أين يُمكن القول بأن سعر الكهرباء رخيص نسبيا. للوصول إلى النتيجة آنفة الذكر نحتاج إلى استخدام 14,164,898 جهاز بتكلفة $16,997,877 وهو ما يُمثل خسارة تُقدر بـ $13,072,014 يوميا للمُنقبين.
By comparison to government-backed global currencies, Bitcoin remains fairly complex for the typical user to acquire and use in regular transactions. Growing interest and significant global investments in Bitcoin wallet and Blockchain technology have nonetheless made buying and selling Bitcoin far more accessible to the average user. And indeed growing acceptance by government entities have ameliorated the ambiguity of legal and regulatory status for Bitcoin and Bitcoin exchanges.
As can be seen from the data on this page, Ethereum’s price has been enormously volatile and therefore highly unpredictable over the short-term. However, longer-term trends are easier to predict, with fundamental metrics such as the total number of developers, community discussion and GitHub pull requests indicating a more accurate future price trend. Other methods to predict the price of Ethereum include metrics such as Network Value to Transaction ratio (NVT ratio) and the relative prices between coins. The method that we find most interesting is in that of the Ethereum-based prediction market, Augur. These predictions source the “wisdom of the crowd” to determine the likelihood of an outcome occurring and provide a significant level of insight into the market sentiment.
^ Beikverdi, A.; Song, J. (June 2015). Trend of centralization in Bitcoin's distributed network. 2015 IEEE/ACIS 16th International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel/Distributed Computing (SNPD). pp. 1–6. doi:10.1109/SNPD.2015.7176229. ISBN 978-1-4799-8676-7. Archived from the original on 26 January 2018.
^ Mooney, Chris; Mufson, Steven (19 December 2017). "Why the bitcoin craze is using up so much energy". The Washington Post. Archived from the original on 9 January 2018. Retrieved 11 January 2018. several experts told The Washington Post that bitcoin probably uses as much as 1 to 4 gigawatts, or billion watts, of electricity, roughly the output of one to three nuclear reactors.
Ethereum is also being used as a platform to launch other cryptocurrencies. Because of the ERC20 token standard defined by the Ethereum Foundation, other developers can issue their own versions of this token and raise funds with an initial coin offering (ICO). In this fundraising strategy, the issuers of the token set an amount they want to raise, offer it in a crowdsale, and receive Ether in exchange. Billions of dollars have been raised by ICOs on the Ethereum platform in the last two years, and one of the most valuable cryptocurrencies in the world, EOS, is an ERC20 token.

^ Jump up to: a b c d "Statement of Jennifer Shasky Calvery, Director Financial Crimes Enforcement Network United States Department of the Treasury Before the United States Senate Committee on Banking, Housing, and Urban Affairs Subcommittee on National Security and International Trade and Finance Subcommittee on Economic Policy" (PDF). fincen.gov. Financial Crimes Enforcement Network. 19 November 2013. Archived (PDF) from the original on 9 October 2016. Retrieved 1 June 2014.
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] 

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.
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.
A wallet stores the information necessary to transact bitcoins. While wallets are often described as a place to hold[93] or store bitcoins, due to the nature of the system, bitcoins are inseparable from the blockchain transaction ledger. A wallet is more correctly defined as something that "stores the digital credentials for your bitcoin holdings" and allows one to access (and spend) them.[7]:ch. 1, glossary Bitcoin uses public-key cryptography, in which two cryptographic keys, one public and one private, are generated.[94] At its most basic, a wallet is a collection of these keys.
J. P. Morgan Chase is developing JPM Coin on a permissioned-variant of Ethereum blockchain dubbed "Quorum".[53] It's designed to toe the line between private and public in the realm of shuffling derivatives and payments. The idea is to satisfy regulators who need seamless access to financial goings-on, while protecting the privacy of parties that don't wish to reveal their identities nor the details of their transactions to the general public.[54] 

لضمان صحّة عمليات التحويل، يقوم نظام البيتكوين بالاحتفاظ بسجل حسابات تُسجل فيه جميع الإجراءات التي تتم على الشبكة يُطلق عليه اسم سلسلة الكُتل (بالإنجليزية: block chain). تتشارك جميع العُقد المتواجدة على شبكة البيتكوين هذا السجل عبر نظام يعتمد على بروتوكول بِتكُيِن. تحتوي سلسلة الكُتل على جميع الإجراءات التي تمت باستخدام بِتكُيِن، وهو ما يُمكن من معرفة الرصيد الذي يملكه كل عنوان على هذه الشبكة. يُطلق على هذا المفهوم وصف السلسلة للترابط المتواجد ما بين الكُتل، حيث تحتوي كل كُتلة على هاش الكُتلة التي تسبقها ويتواصل الأمر إلى غاية الوصول إلى الكُتلة الأولى التي يُطلق عليها اسم "كتلة التكوين" (بالإنجليزية: genesis block) . تكوين السلسلة بهذه الطريقة يجعل من مهمة تغيير أي كُتلة بعد مرور مُدة مُعينة على إنشائها في غاية الصعوبة، حيث أن تغيير أي كُتلة يتطلب تغيير كل الكُتل التي تليها بسبب الحاجة إلى إعادة حساب هاش كل كُتلة لتحديث قيمة هاش الكُتلة السابقة فيها. هذه الخاصية هي ما يجعل من مُشكل الإنفاق المُتكرر لنفس العُملات في غاية الصعوبة على بِتكُيِن، بل ويُمكن اعتبار سلسلة الكُتل العمود الفقري الذي لا يُمكن لعُملة بِتكُيِن الوقوف من دونه[10].


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]
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]
^ Beikverdi, A.; Song, J. (June 2015). Trend of centralization in Bitcoin's distributed network. 2015 IEEE/ACIS 16th International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel/Distributed Computing (SNPD). pp. 1–6. doi:10.1109/SNPD.2015.7176229. ISBN 978-1-4799-8676-7. Archived from the original on 26 January 2018.
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.
According to the European Central Bank, the decentralization of money offered by bitcoin has its theoretical roots in the Austrian school of economics, especially with Friedrich von Hayek in his book Denationalisation of Money: The Argument Refined,[127] in which Hayek advocates a complete free market in the production, distribution and management of money to end the monopoly of central banks.[128]:22
Nigel Dodd argues in The Social Life of Bitcoin that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control.[131] Dodd quotes a YouTube video, with Roger Ver, Jeff Berwick, Charlie Shrem, Andreas Antonopoulos, Gavin Wood, Trace Meyer and other proponents of bitcoin reading The Declaration of Bitcoin's Independence. The declaration includes a message of crypto-anarchism with the words: "Bitcoin is inherently anti-establishment, anti-system, and anti-state. Bitcoin undermines governments and disrupts institutions because bitcoin is fundamentally humanitarian."[131][130]
Because of bitcoin's decentralized nature and its trading on online exchanges located in many countries, regulation of bitcoin has been difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a de facto ban.[167] The legal status of bitcoin varies substantially from country to country and is still undefined or changing in many of them. Regulations and bans that apply to bitcoin probably extend to similar cryptocurrency systems.[168]
• 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. 

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]
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