Sessions CodeIgniter vs sessions PHP

[eluser]kurucu[/eluser]
Why not, because you don't understand it or because you see something more in the $_SESSIONS array?

The session library provides the following:
- Automatic session creation/destruction
- The ability to store any number of variables against the session
- The ability to retrieve those variables
- The ability to set flash variables that only persist for one request
- The ability to choose to store the data in the cookie or in the local database
- The ability to encrypt the cookie data

There is functionality there that PHP's native sessions do not provide, and in a well packaged class.

You can easily use them in a similar way by autoloading the session, and using set_userdata and userdata to set and retrieve variables, rather than in array elements.