What does the assignment of each HTTP method mean and in what cases is it used?

Main HTTP methods and their purpose:

• GET — retrieve a resource. Used for requesting data without changing the server's state.
• POST — create a new resource or perform an operation that changes the server's state.
• PUT — replace an existing resource or create it if it does not exist.
• DELETE — delete a resource.
• PATCH — partially update a resource.
• HEAD — retrieve only the headers of a resource, without the body.

Usage:

• GET — when data needs to be retrieved.
• POST — when creating new records or performing actions.
• PUT — when the entire resource needs to be replaced.
• PATCH — for partial updates.
• DELETE — for deletion.
• HEAD — to check the existence of a resource or its metadata without downloading the body.