Simple definition
The HTTP PUT method creates or replaces the representation of a specified target resource.
Purpose and use
PUT requests creation or replacement of a target resource's state using the supplied representation.
How does it work?
It is idempotent: repeated identical requests intend the same final effect, although responses and logs may differ.
Example and verification
For concurrent updates, check supported preconditions, such as an ETag used with If-Match.
Points to watch
PUT does not automatically mean partial modification. Omitting a field can have different consequences under the API contract.
In short
Using PUT requires understanding the expected representation and the server's replacement behavior.