How To Use Session

Session is a period of time given to a visitor when he or she request a page from your web server. By using session, you will be able to collect information entered by user on your web site such as username or password. Thus, when a visitor enter a username on your login page, this information can be used later on for your entire web site.

The function to start a session in PHP is session_start( ). It has to be placed right on top of the page before any皜PHP or HTML code.

When you tell PHP to start a session, it will randomly generate an ID to be stored into your visitor's web browser as a cookie. So, when he or she browse to another page within your web site, their web browser will send those ID to your web server to identify them.

You can view your own session ID by typing $PHPSESSID.

Many web developer including myself like to register a session instead of using hidden fields, cookies or even worst passing sensitive information via URLs to store user preferences and login system. It is more efficient and secure doing it that way.

In PHP, you can register a session by using session_register( ). Let say that you are going to build a login system and use their username for your entire web site setting preferences.

The above code is just an example of how to register a session in a login system. It is not a complete login system script.

So, after a user had successfully enter their username and password, first of all, you had to register the userName using session_register( ) and then assign the value to it. When this code is executed, PHP will store this session ID to user's computer. It will be accessible as long as the session is still active.