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To form a distributed timestamp server as a peer-to-peer network, bitcoin uses a proof-of-work system. This work is often called bitcoin mining. Requiring a proof of work to accept a new block to the blockchain was Satoshi Nakamoto's key innovation. The mining process involves identifying a block that, when hashed twice with SHA-256, yields a number smaller than the given difficulty target. While the average work required increases in inverse proportion to the difficulty target, a hash can always be verified by executing a single round of double SHA-256. For the bitcoin timestamp network, a valid proof of work is found by incrementing a nonce until a value is found that gives the block's hash the required number of leading zero bits. Once the hashing has produced a valid result, the block cannot be changed without redoing the work. As later blocks are chained after it, the work to change the block would include redoing the work for each subsequent block. Majority consensus in bitcoin is represented by the longest chain, which required the greatest amount of effort to produce. If a majority of computing power is controlled by honest nodes, the honest chain will grow fastest and outpace any competing chains.

Mining pools may contain hundreds or thousands of miners using specialized protocols. In all these schemes B stands for a block reward minus pool fee and p is a probability of finding a block in a share attempt (p = 1/D, where D is current block difficulty). A pool can support "variable share difficulty" feature, which means that a miner can select the share target (the lower bound of share difficulty) on his own and change p accordingly. The list of pools for mining is extensive – in the world there are more than a thousand. The vast majority of users work through bitcoin pools. The level of complexity of the production of this currency is so high that alone, even with a supercomputer profit is not obtained. Therefore, all new pools are formed. There are other cryptocurrencies, younger than bitcoin, which are faster and easier to mine. But they do not have real value in the network, and they can only earn with the hope that in the future their rate will grow, and this is more like speculative mining.