In May 1997, Adam Back proposed Hashcash, based on a proof-of-work system, to counter spam and DoS attacks. Subsequently, a similar system in another implementation became part of the procedure for creating new blocks in the Bitcoin network.

On January 3, 2009, the first block was generated, for which the first reward of 50 bitcoins was issued, and the source code of the client software was published. The first transaction involving the transfer of bitcoins took place on January 12, 2009 — Satoshi Nakamoto sent Hal Finney 10 bitcoins. The first exchange of bitcoins for national currency occurred in September 2009 — Martti Malmi sent 5050 bitcoins to a user with the alias NewLibertyStandard, for which he received $5.02 in his PayPal account. NewLibertyStandard suggested using the cost of electricity spent on generation to evaluate bitcoins.