Proof-of-work is what secures Bitcoin and, at a deep level, allows the decentralized mining of Bitcoin. Finding a proof-of-work gives a miner the right to put the attached block into the blockchain. As proof-of-work is very rare, this is not an easy task. But because proof-of-work is objective and easy to verify, anyone can be a miner if they so choose.
Proof-of-work is what secures Bitcoin and, at a deep level, allows the decentralized mining of Bitcoin. Finding a proof-of-work gives a miner the right to put the attached block into the blockchain. As proof-of-work is very rare, this is not an easy task. But because proof-of-work is objective and easy to verify, anyone can be a miner if they so choose.