An API Gateway is a server that acts as an entry point for clients to interact with multiple backend services in a microservices architecture. It consolidates various APIs into a single interface, streamlining communication between clients and services. API Gateways manage requests, route them to the appropriate service, and handle authentication, load balancing, and rate limiting. This is essential in a distributed system, where individual microservices need to be orchestrated and protected. By providing security and operational control, API Gateways help optimize performance and prevent unauthorized access. Popular API Gateway solutions include AWS API Gateway, Kong, and NGINX.