Proof of Authority (PoA) blockchains rely on a fixed number of trusted validators instead of mining or staking, making transactions fast and efficient. VeChain, xDai, and TomoChain use the PoA consensus algorithm to ensure security while reducing energy consumption. This model is ideal for enterprise solutions, supply chains, and private networks where reliability matters more than decentralization. PoA blockchains offer high-speed transactions with lower costs.