4) mining:

- mining is literally just a computer (node) trying over and over to calculate a hash (a string of numbers and letters) that satisfies the requirements of the Bitcoin software
- for example, the requirement might be to calculate a hash that starts with 19 zeroes
- if the correct hash is found, the miner publishes the block and its corresponding hash to the Bitcoin network. other miners review the block and if the majority agrees, the block is committed to the blockchain
- miners are incentivized to “mine” because they receive Bitcoin each time they mine a new block