How to Use the PHP Function Session_CreateID

php function session_create_id is used to generate a unique collistion free session id for the current session. This session id is stored in the $_SESSION superglobal and can be accessed across multiple web requests. This is useful for tracking a user throughout your site.

In order to use a session you must first start it with session_start(). Then you can call session_read() to retrieve the existing data stored in your session. You can also set up auto sessions where the session is created automatically each time a user visits your website.

When a visitor opens your website they will usually enter their login information into your form or submit a request on the page. This request is then sent to the server which authenticates the login credentials and creates a new session on the user's computer. The session id is then passed back to the browser in the form of a cookie called PHPSESSID. The session variables that are initialized on the page they visit will be accessible from all other pages they access during their visit until the session expires.

To close and read a session you must register a session save handler with the session_set_save_handler() function. This handler can either be a built in save handler provided by PHP (such as SQLite or Memcached) or it can be a custom handler that is defined with the session_set_save_handler(). The read callback will return the value in a serialized format that can then be unserialized by PHP to automatically populate the $_SESSION superglobal.