API Gateway plays a crucial role in managing and facilitating communication between different services in a microservices architecture or between clients and servers. Request and response transformation in API Gateway involves modifying the format or content of incoming requests or outgoing responses to meet the requirements of both the clients and the services.

Let's explore this concept with a use case. Imagine you are managing an e-commerce website, and you want to implement request and response transformations to improve security and customize the response.