Proof of Work is a consensus mechanism used in blockchain networks, primarily to validate transactions and secure the network. It requires participants, known as miners, to solve complex mathematical problems. This process consumes computational power and energy, ensuring that only those who invest resources can add new blocks to the blockchain. Once a miner successfully solves the problem, they broadcast their solution to the network. Other miners verify the solution, and if confirmed, the new block is added to the blockchain. This method helps prevent fraud and attacks, as altering any part of the blockchain would require immense computational effort.