(PHP 4, PHP 5, PHP 7) Get and/or set the current session name

(PHP 4, PHP 5, PHP 7) Start new or resume existing session

(PHP 4 >= 4.0.4, PHP 5, PHP 7) Write session data and end session

(PHP 5 >= 5.4.0, PHP 7) Read session data

(PHP 4, PHP 5, PHP 7) Free all session variables

(PHP 5 >= 5.5.1, PHP 7) Return a new session ID

(PHP 4 >= 4.2.0, PHP 5 <= 5.1.2) Get unique id

(PHP 5 >= 5.6.0, PHP 7) Re-initialize session array with original values

(PHP 4, PHP 5 < 5.4.0) Find out whether a global variable is registered in a session

(PHP 5 >= 5.4.0, PHP 7) Write session data