What does it mean for an HTTP method to be idempotent?

• A. It never changes server state.
• B. It can be repeated without any server processing.
• C. Repeating the same request multiple times has the same effect as a single request.
• D. Only safe methods can be idempotent.

Answer: (C)

Idempotence means that sending the same request multiple times has the same effect as sending it once. In HTTP, this means repeating the exact same call won’t stack or multiply changes after the first successful one. For example, issuing a PUT to set a resource to a specific state will keep that state the same if you repeat the request again, so multiple identical requests don’t create additional changes. GET, DELETE, and certain other methods are designed to be idempotent for similar reasons, while POST isn’t because each request can create a new resource.

So the best description is that repeating the same request multiple times has the same effect as a single request. The idea isn’t that there’s no processing, but that the outcome doesn’t accumulate with repeats.