In Hour 15, "Restricting Access to Your Applications," we looked at using cookies to store user-related values, but once again, PHP is one step ahead of us. PHP contains numerous functions for managing user sessions, which can be stored in the $_SESSION superglobal. Sessions use techniques similar to those explored in the preceding hour but build them into the language; thus, saving state is as easy as calling a function.
In this hour, you will learn
What session variables are and how they work
How to start or resume a session
How to store variables in a session
How to destroy a session
How to unset session variables