Zii Or Web/widgets

Hi to everyone

I can’t understand how core widgets are grouping

There are widget libraries both zii/widgets and web/widgets in yii framework folder

How can I know where is what widget and where rather than seeking in folders?

Is there any logic of this folder structure?

What is the meaning of zii (like Yii! = Yes it is! , Gii= generator of Yii etc) ?


Anyone please?