What is the difference between SESSION and POST in PHP?

Answer 1

POST:

Taken from the HTTP 1.0 RFC (#1945:8.3)

The POST method is used to request that the destination server accept

the entity enclosed in the request as a new subordinate of the

resource identified by the Request-URI in the Request-Line. POST is

designed to allow a uniform method to cover the following functions:

o Annotation of existing resources;

o Posting a message to a bulletin board, newsgroup, mailing list,

or similar group of articles;

o Providing a block of data, such as the result of submitting a

form [3], to a data-handling process;

o Extending a database through an append operation.

SESSION:

http://us2.php.net/manual/en/reserved.variables.php#reserved.variables.session

An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $_SESSION; to access it within functions or methods, as you do with $HTTP_SESSION_VARS.

$HTTP_SESSION_VARS contains the same information, but is not a superglobal. (Note that $HTTP_SESSION_VARS and $_SESSION are different variables and that PHP handles them as such)

If the register_globals directive is set, then these variables will also be made available in the global scope of the script; i.e., separate from the $_SESSION and $HTTP_SESSION_VARS arrays. For related information, see the security chapter titled Using Register Globals. These individual globals are not superglobals.