Difference between POST, PUT and DELETE method in controller

Question

Hello 

 

When to user POST, PUT and DELETE method in controller.

 

POST is used to send data to a server to create/update a resource then why there is PUT and DELETE. 

 

PUT is used to update the resource. we can do same with POST method the why PUT.

 

another doubt: 

The DELETE method deletes the specified resource. 

 we can write the delete in POST method then why delete.

 

Pease clear in both in MVC and also in Web API.

 

Thanks in advance.