!!! Overview[1]
[{$pagename}] is a [HTTP Method] which requests that the server accept the entity enclosed in the request as a new subordinate of the web resource identified by the [URI]. 

The data POSTed might be, for example, an annotation for existing resources; a message for a bulletin board, newsgroup, mailing list, or comment thread; a block of data that is the result of submitting a web form to a data-handling process; or an item to add to a database.

!! [{$pagename}] do NOT [Cache]]
An interesting point on [{$pagename}] vs [HTTP GET] is that [{$pagename}] do NOT [Cache]] which can be an issue for some [API] calls.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [Request methods|Wikipedia:Hypertext_Transfer_Protocol#Request_methods|target='_blank'] - based on information obtained 2016-05-21-