Let’s make the computer do this for us.
OK, that probably took you a lot longer. Now imagine finding a hash that starts with five or ten zeroes. This is the challenge that the bitcoin network poses to miners when they want to submit new blocks with transactions.
Miners gather all the information they want to put in a block such as the previous block header hash, a hash of transactions to be included in block (including the coinbase transaction), time, and combine it with a random number called a nonce (which stands for “number only used once”). They send all of this into the hash function to create something called the block hash.
When bitcoin first launched, miners would cycle through the nonce in the block header by incrementing the data by 1 in the 32-bit field. But since miners are so powerful now and difficulty is so high, they cycle through this pretty quickly and normally don’t find a solution below the
target difficulty What is target difficulty?
.So what miners need to do is change other parts of the block header, such as the time or transactions included in the block.