I am a very very beginner with blockchain. I've read a lot of articles and can't understand one thing. When data miner is creating new block, the hash of such block must meet certain requirements. As I understand this is the key difficulty for creating new block. However, as a programmer I know that it is very easy to create new hash. Can anyone explain what is the reason of such requirements?
The hash must be less than or equal to a certain target hash. This is to reduce the probability that any random hash you choose will be a valid hash with valid work. The whole point of this is to prove that you (as a miner) did, on average, a certain number of hashes (work) in order to find the block.