Framework with a small footprint
CodeIgniter 3 has a 2MB download, including the user guide.
Simple solutions over complexity
CodeIgniter encourages MVC, but does not force it on you.
The CodeIgniter User Guide comes with the download. It contains an introduction, tutorial, a number of "how to" guides, and then reference documentation for the components that make up the framework.
CodeIgniter consistently outperforms most of its competitors.
We take security seriously, with built-in protection against CSRF and XSS attacks.
Nearly zero configuration
Much of the CodeIgniter configuration is done by convention, for instance putting models in a "models" folder. There are still a number of configuration options available, through scripts in the "config" folder.