An "API gateway" facilitates communication and manages requests between clients and microservices architectures. It acts as a single entry point for external clients to access various microservices, handling tasks like routing, authentication, and rate limiting. By centralizing these functions, an API gateway enhances security, controls traffic, and ensures efficient resource utilization. Additionally, it simplifies the client-side experience by abstracting the complexity of interacting with multiple microservices. This contributes to faster development cycles and improved scalability within modern applications using microservices frameworks.