PoW (Proof of Work)
In short: Proof of Work (PoW) is a consensus mechanism based on computational effort. Miners compete to find a value that makes a block’s hash fall below a…
Proof of Work (PoW) is a consensus mechanism based on computational effort. Miners compete to find a value that makes a block’s hash fall below a difficulty target, and the first to succeed adds the block and earns a reward, while every other node can check the result with little effort.
Why it matters
Bitcoin made proof of work the foundation of a cryptocurrency, and networks such as Litecoin and Dogecoin use it too. Its security comes from cost: to rewrite history, an attacker would need to control the majority of the network’s hashing power, which is known as a 51% attack. That same cost is the main criticism of PoW, because mining consumes large amounts of electricity. The protocol adjusts the difficulty automatically, so blocks keep arriving at a roughly steady pace as miners join or leave.
Example
Think of a lottery where each ticket is one hash attempt. Every miner’s hardware tries a huge number of attempts per second, changing a number in the block header each time. Only a hash below the target wins. Finding one is hard, but anyone can check a winning hash with a single calculation. If more miners join and blocks start coming too fast, the difficulty rises to slow them back down.