The Proof of Work (PoW) is a consensus algorithm used in blockchain systems, such as Bitcoin, to validate and confirm transactions on the network. This method requires miners to solve complex mathematical problems to create new blocks in the blockchain and, in return, they are rewarded with cryptocurrencies.

How Proof of Work Works:

1. Problem Solving: Miners compete with each other to solve a highly complex mathematical problem. This problem requires a significant amount of computational power and is difficult to solve, but easy to verify once the solution is found.
2. Block Validation: Once a miner solves the problem, they create a new block in the blockchain and add the verified transactions to that block.
3. Solution Proof: Other nodes in the network quickly verify whether the solution proposed by the miner is correct. If it's correct, the new block is accepted by the network.
4. Reward: The miner who solves the problem and validates the block is rewarded with a certain amount of cryptocurrencies (e.g., Bitcoin) and transaction fees from the transactions included in that block.
5. Ongoing Competition: The competition to solve problems and create blocks continues, ensuring the continuity of the blockchain and the validation of new transactions.

Proof of Work is known for its high security and resistance to attacks, as an attacker would need to control a majority of the network's computational power to alter the blockchain. However, it also requires a significant amount of energy and computational resources, which has led to the development of other more energy-efficient consensus algorithms, such as Proof of Stake (PoS).