Proof of Authority (PoA) is a consensus mechanism used in blockchain networks where a limited number of pre-approved nodes, or validators, are given the authority to create new blocks and validate transactions. This system relies on the reputation and identity of these validators, making it efficient and faster than other methods like Proof of Work. In PoA, the validators are typically known entities, which helps to reduce the risk of malicious activities. This model is often used in private or consortium blockchains, where trust among participants is established, allowing for quicker transaction processing and lower energy consumption compared to traditional mining methods.