rest put is for create or update

hi,

i was reading below that rest webservices put is for creating
https://www.tutorialspoint.com/restful/restful_introduction.htm

I remember reading some where POST is for create and PUT is to update.

can you please advise which HTTP method for which?

Sr.No.      HTTP Method      URI      Operation      Operation Type
1      GET      /UserService/users      Get list of users      Read Only
2      GET      /UserService/users/1      Get User with Id 1      Read Only
3      PUT      /UserService/users/2      Insert User with Id 2      Idempotent
4      POST      /UserService/users/2      Update User with Id 2      N/A
5      DELETE      /UserService/users/1      Delete User with Id 1      Idempotent
6      OPTIONS      /UserService/users      List the supported operations in web service      Read Only

why it says operation type for POST is N/A where as put is idempotent. what it means?

for working on rest examples why we need both below entries


<dependency>
                  <groupId>javax.ws.rs</groupId>
                  <artifactId>javax.ws.rs-api</artifactId>
                  <version>2.0.1</version>
            </dependency>
            <dependency>
                  <groupId>org.apache.cxf</groupId>
                  <artifactId>cxf-rt-rs-service-description</artifactId>
                  <version>3.0.0-milestone1</version>
            </dependency>


below is fine
<groupId>javax.ws.rs</groupId>
                  <artifactId>javax.ws.rs-api</artifactId>

but why we need cxf as below as well in pom.xml?