What is proof of work?

What Is Proof of Work?

Proof of work (PoW) is a way for a blockchain to agree on the next block without a central authority. Miners spend computing power to solve a hard puzzle. The first to find a valid solution gets to add the block and claim the reward. Others then build on that block. This makes attacking the chain costly because you would need more power than the rest of the network.

How It Works

Each block has a target: its hash must be below a certain value. Miners change a number (nonce) in the block and hash it repeatedly until they get a hash that meets the target. Difficulty is adjusted so blocks are produced on a schedule. More total mining power means higher difficulty.

Pros and Cons

PoW is battle-tested (Bitcoin has used it since 2009) and secure. The downside is high energy use. Many newer chains use proof of stake instead, which does not require mining hardware. Both aim to achieve consensus: everyone agrees on the same history of transactions.