Proof of Work (PoW) is a consensus mechanism where miners compete to solve complex mathematical puzzles. The first to solve the puzzle gets to add the next block and receive the reward.
How PoW works: Miners collect pending transactions, compete to find valid hash, winner broadcasts block to network, other nodes verify and accept, and winner receives block reward plus fees.
PoW advantages: Battle-tested security (Bitcoin since 2009), truly decentralized (anyone can mine), and objective measure of work done.
PoW disadvantages: High energy consumption, specialized hardware requirements (ASICs), potential for mining centralization, and slower finality than PoS.