A HTTP method is said to be idempotent if it returns the same result every time. HTTP methods GET, PUT, DELETE, HEAD, and OPTIONS are idempotent method and we should implement our application to make sure these methods always return same result. HTTP method POST is non-idempotent method and we should use post method when implementing something that changes with every request.
For example, to access an HTML page or image, we should use GET because it will always return the same object but if we have to save customer information to database, we should use POST method. Idempotent methods are also known as safe methods and we don’t care about the repetitive request from the client for safe methods.