Which HTTP methods do not guarantee the same result upon multiple repeated requests?

HTTP methods that do not guarantee idempotency (meaning a repeated request can lead to different results) include:

• POST — typically used for creating resources or performing operations with side effects. Repeating a POST can create multiple resources or change the server's state.
• PATCH — used for partial updates to a resource; repeated requests can change the state multiple times.

In contrast, methods GET, PUT, DELETE, HEAD, OPTIONS, TRACE are considered idempotent, meaning repeated requests should not change the result or server state after the first call.

Example:

• Repeating a POST request to create an order may result in multiple orders being created.
• Repeating a GET request always returns the same representation of the resource (assuming the server has not changed).