Request throttling and rate limiting help prevent abuse or excessive usage of your Web API. In ASP.NET Core Web API, you can implement request throttling and rate limiting by using middleware or third-party libraries. Middleware, such as AspNetCoreRateLimit, intercepts incoming requests and checks if the client has exceeded the defined limits. It can be configured to limit requests based on IP addresses, client IDs, or other criteria. When the limit is reached, the middleware can return a response with an appropriate status code or take other actions, such as delaying or rejecting the request. Third-party libraries like Polly can also be used to implement more complex rate limiting strategies. Implementing request throttling and rate limiting helps ensure the stability and availability of your Web API.