POST means "create new" as in "Here is the input for creating a user, create it for me". PUT means "insert, replace if already exists" as in "Here is the data for    Cps test    user 5". You POST to example.com/users since you don't know the URL of the user yet, you want the server to create it.

Use PUT when you want to modify a single resource which is already a part of resources collection. PUT overwrites the resource in its entirety. Use PATCH if request updates part of the resource. Use POST when you want to add a child resource under resources collection