Yii is a PHP framework
based on the MVC (model-view-controller) design pattern. It comes with:
And a lot more, which saves us the hassle of writing all of that ourselves. Yes, it also has a tool called Gii to automatically generate
models and CRUD code from the database, plus there are over 1300 free extensions
to add more functionality, for example for Twitter Bootstrap, GeoIP, PHPMailer/SwiftMailer, TinyMCE, Smarty/Twig, etc.
If you want to create SB2 plugins, there's a simple example in the documentation
, which you can save as application/plugins/DemoPlugin.php and then enable it under Administration > Settings > Plugins. The included Community Bans plugin is more complex (and unfinished, but you can enable it and see what it does so far).
You're right, most people will probably just change the CSS to make it look different, so I am looking into the possibility of adding CSS files to existing themes, so you don't have to copy the HTML. But due to starting a new job my time has been limited.