Rate limiting helps prevent abuse or excessive use of an API by limiting the number of requests a client can make within a specified time frame. You can implement rate limiting in ASP.NET Core by using middleware or third-party libraries such as AspNetCoreRateLimit. The middleware intercepts incoming requests, checks the client's request rate, and either allows or denies the request based on predefined limits. Rate limiting can be based on IP addresses, client IDs, or other criteria.