What does PUT do in REST semantics?

• A. Partial update
• B. Delete resource
• C. Replaces a resource completely; if it doesn't exist, create a new one
• D. Retrieve resource

Answer: (C)

In REST, PUT is the operation used to place a complete representation of a resource at a specific URI. It replaces the resource at that location with exactly what you send, and it is idempotent—sending the same PUT payload multiple times yields the same result. If a resource at that URI doesn’t exist yet, the server can create it using the provided representation. This behavior—full replacement at a known URI, with possible creation if absent—best matches the described option. It also contrasts with POST (which creates a new resource at a server-defined URL and isn’t inherently idempotent) and PATCH (which is for partial updates rather than full replacement).