What are the triggers that cause a browser to use a HTTP method ?

HTTP POST

• Allows the client to send data of unlimited length to server
• Usage : Useful when sending sensitive information like, Credit card numbers

HTTP GET

• Retrieves whatever information sent in Request URI

HTTP HEAD

• It is a GET request that returns no body in the response, on the request header fields.
• The client sends a HEAD request when it wants to see only the headers of a response, such as Content Type or Content-Length.
• This method counts the number of output bytes in the response to set the Content-Length header accurately.
• Usage :
• can be used for obtaining meta-information about the entity implied by the request without transferring the entity-body itself.
• often used for testing hypertext links for validity, accessibility, and recent modification.