A DeFi aggregator is a platform that consolidates various decentralized finance services, offering users access to multiple protocols and assets in one interface. These platforms help users find the best yields, lowest fees, and most efficient liquidity by sourcing opportunities from across different DeFi protocols. Aggregators improve the user experience by simplifying interactions with DeFi applications and ensuring optimized financial outcomes, making it easier for individuals to navigate the complex world of decentralized finance.