Despite having similar needs, there is a good deal of diversity in how chip designers build their hashing engines, says Hanke, who also served as the chief technology officer of a now-defunct mining rig manufacturer called CoinTerra. For example, Bitmain uses pipelining—a strategy that links the steps in a process into a chain in which the output of one step is the input of the next. Bitmain competitor BitFury has chosen not to use that technology.
According to the Library of Congress, an "absolute ban" on trading or using cryptocurrencies applies in eight countries: Algeria, Bolivia, Egypt, Iraq, Morocco, Nepal, Pakistan, and the United Arab Emirates. An "implicit ban" applies in another 15 countries, which include Bahrain, Bangladesh, China, Colombia, the Dominican Republic, Indonesia, Iran, Kuwait, Lesotho, Lithuania, Macau, Oman, Qatar, Saudi Arabia and Taiwan.[166]

Bitcoin is a peer-to-peer version of electronic cash that allows payments to be sent directly from one party to another without going through a financial institution. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. – Satoshi Nakamoto
Miners found other advantages. The cool winters and dry air helped reduce the need for costly air conditioning to prevent their churning servers from overheating. As a bonus, the region was already equipped with some of the nation’s fastest high-speed internet, thanks to the massive fiber backbone the data centers had installed. All in all, recalls Miehe, the basin was bitcoin’s “killer app.”

Several deep web black markets have been shut by authorities. In October 2013 Silk Road was shut down by U.S. law enforcement[35][36][37] leading to a short-term decrease in the value of bitcoin.[38] In 2015, the founder of the site was sentenced to life in prison.[39] Alternative sites were soon available, and in early 2014 the Australian Broadcasting Corporation reported that the closure of Silk Road had little impact on the number of Australians selling drugs online, which had actually increased.[40] In early 2014, Dutch authorities closed Utopia, an online illegal goods market, and seized 900 bitcoins.[41] In late 2014, a joint police operation saw European and American authorities seize bitcoins and close 400 deep web sites including the illicit goods market Silk Road 2.0.[42] Law enforcement activity has resulted in several convictions. In December 2014, Charlie Shrem was sentenced to two years in prison for indirectly helping to send $1 million to the Silk Road drugs site,[43] and in February 2015, its founder, Ross Ulbricht, was convicted on drugs charges and faces a life sentence.[44]
Bitcoin miners were now caught in the same vicious cycle that real miners confront—except on a much more accelerated timeframe. To maintain their output, miners had to buy more servers, or upgrade to the more powerful servers, but the new calculating power simply boosted the solution difficulty even more quickly. In effect, your mine was becoming outdated as soon as you launched it, and the only hope of moving forward profitably was to adopt a kind of perpetual scale-up: Your existing mine had to be large enough to pay for your next, larger mine. Many miners responded by gathering into vast collectives, pooling their calculating resources and sharing the bitcoin rewards. Others shifted away from mining to hosting facilities for other miners. But whether you were mining or hosting, mining entered “a scaling race,” says Carlson, whose own operations marched steadily from 250 kilowatts to 1.5 megawatts to 5 megawatts. And it was a race: Any delay in getting your machines installed and mining simply meant you’d be coming on line when the coins were even harder to mine.
Steve Wright and John Stoll: The Dam Masters Wright, left, and Stoll, pictured at the Rocky Reach Dam, are general manager and head of customer utilities with the Chelan County Public Utility District, respectively. In the past year, miners have made inquiries or requests for power totaling two-thirds as much as the basin’s three county utilities now generate. | Patrick Cavan Brown for Politico Magazine

Bitcoin and other cryptocurrencies have been identified as economic bubbles by at least eight Nobel Memorial Prize in Economic Sciences laureates, including Robert Shiller,[191] Joseph Stiglitz,[192] and Richard Thaler.[193][13] Noted Keyensian economist Paul Krugman wrote in his New York Times column criticizing bitcoin, calling it a bubble and a fraud;[194] and professor Nouriel Roubini of New York University called bitcoin the "mother of all bubbles."[195] Central bankers, including former Federal Reserve Chairman Alan Greenspan,[196] investors such as Warren Buffett,[197][198] and George Soros[199] have stated similar views, as have business executives such as Jamie Dimon and Jack Ma.[200]
Across the Mid-Columbia Basin, miners faced an excruciating dilemma: cut their losses and walk, or keep mining for basically nothing in the hopes that the cryptocurrency market would somehow turn around. Many smaller operators simply folded and left town—often leaving behind trashed sites and angry landlords. Even larger players began to draw lines in the sand. Carlson started moving out of mining and into hosting and running sites for other miners. Others held on. Among the latter was Salcido, the Wenatchee contractor-turned-bitcoin miner who grew up in the valley. “What I had to decide was, do I think this recovers, or does the chart keep going like this and become nothing?” Salcido told me recently. We were in his office in downtown Wenatchee, and Salcido, a clean-cut 43-year-old who is married with four young kids, was showing me a computer chart of the bitcoin price during what was one of the most agonizing periods of his life. “Month over month, you had to make this decision: Am I going to keep doing this, or am I going to call it?” 

Bitcoin mining is the process of updating the ledger of Bitcoin transactions known as the blockchain. Mining is done by running extremely powerful computers (known as ASICs) that race against other miners in an attempt to guess a specific number. The first miner to guess the number gets to update the ledger of transactions and also receives a reward of newly minted Bitcoins (currently the reward is 12.5 Bitcoins).
The bitcoin blockchain is a public ledger that records bitcoin transactions.[64] It is implemented as a chain of blocks, each block containing a hash of the previous block up to the genesis block[a] of the chain. A network of communicating nodes running bitcoin software maintains the blockchain.[30]:215–219 Transactions of the form payer X sends Y bitcoins to payee Z are broadcast to this network using readily available software applications.