As a cryptocurrency attracts more interest, mining becomes harder and the amount of coins received as a reward decreases. For example, when Bitcoin was first created, the reward for successful mining was 50 BTC. Now, the reward stands at 12.5 Bitcoins. This happened because the Bitcoin network is designed so that there can only be a total of 21 mln coins in circulation.

Bitcoin is pseudonymous rather than anonymous in that the cryptocurrency within a wallet is not tied to people, but rather to one or more specific keys (or "addresses").[41] Thereby, bitcoin owners are not identifiable, but all transactions are publicly available in the blockchain. Still, cryptocurrency exchanges are often required by law to collect the personal information of their users.[citation needed]

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In cryptocurrency networks, mining is a validation of transactions. For this effort, successful miners obtain new cryptocurrency as a reward. The reward decreases transaction fees by creating a complementary incentive to contribute to the processing power of the network. The rate of generating hashes, which validate any transaction, has been increased by the use of specialized machines such as FPGAs and ASICs running complex hashing algorithms like SHA-256 and Scrypt.[30] This arms race for cheaper-yet-efficient machines has been on since the day the first cryptocurrency, bitcoin, was introduced in 2009.[30] With more people venturing into the world of virtual currency, generating hashes for this validation has become far more complex over the years, with miners having to invest large sums of money on employing multiple high performance ASICs. Thus the value of the currency obtained for finding a hash often does not justify the amount of money spent on setting up the machines, the cooling facilities to overcome the enormous amount of heat they produce, and the electricity required to run them.[30][31]

Cryptocurrencies are experiencing a moment of unprecedented attention and speculation for several reasons. 1) The value of Bitcoin has been steadily climbing through 2017, with Ether seemingly poised to overtake the cryptocurrency giant any day; 2) Blockchain technology has purposes above and beyond cryptocurrency, and has been hailed by some as the backbone of the future financial system; 3) The increasing number of people who see cryptocurrency as a form of investment similar to gold. If cryptocurrencies stabilize in value, buying Bitcoin or Ether has the potential to be a worthy venture. 
Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain.[29] Blockchains solve the double-spending problem without the need of a trusted authority or central server, assuming no 51% attack (that has worked against several cryptocurrencies).


In April 2019, a UK corporate filing stated that Coinbase's non-U.S. revenue grew 20% to €153 million (U.S.$173 million) in 2018 resulting in a net profit of €6.6 million.[37] Coinbase UK CEO Zeeshan Feroz said the company's non-U.S. operations accounted for nearly one-third of the company's overall revenue and Reuters estimated that the company's global revenue totaled "around $520 million" in 2018.[38] 


The novel hybrid consensus-based TrueChain tends to rely on POW consensus for random node selection, instead of using the slow chain mechanism to ensure security like Thunder.Although TrueChain has released dozens of Dapps, the number of its addresses (including active ones)and transactions is small. After the mainnet is launched, the project has run out of short-term bullish factors, which, plus the underdevelopment of its ecosystem, leads to a price slump within a short period of time. It will take some time for investors to regain confidence.