The Process of Verifying BTC Transactions

[Kakashi2020]

In order for bitcoin miners to actually earn bitcoin from verifying transactions, two things have to occur. First, they must verify one megabyte (MB) worth of transactions, which can theoretically be as small as one transaction but are more often several thousand, depending on how much data each transaction stores.

Second, in order to add a block of transactions to the blockchain, miners must solve a complex computational math problem, also called a "proof of work." What they're actually doing is trying to come up with a 64-digit hexadecimal number, called a "hash," that is less than or equal to the target hash. Basically, a miner's computer spits out hashes at different rates—megahashes per second (MH/s), gigahashes per second (GH/s), or terahashes per second (TH/s)—depending on the unit, guessing all possible 64-digit numbers until they arrive at a solution. In other words, it's a gamble.

The difficulty level of the most recent block as of August 2020 is more than 16 trillion. That is, the chance of a computer producing a hash below the target is 1 in 16 trillion. To put that in perspective, you are about 44,500 times more likely to win the Powerball jackpot with a single lottery ticket than you are to pick the correct hash on a single try. Fortunately, mining computer systems spit out many hash possibilities. Nonetheless, mining for bitcoin requires massive amounts of energy and sophisticated computing operations.

The difficulty level is adjusted every 2016 blocks, or roughly every 2 weeks, with the goal of keeping rates of mining constant.4 That is, the more miners there are competing for a solution, the more difficult the problem will become. The opposite is also true. If computational power is taken off of the network, the difficulty adjusts downward to make mining easier.