Here are all wiki articles from "Understanding" series by Yii wiki contributors:

• Understanding Virtual Attributes and get/set methods by SJFriedl
• Understanding Autoloading, Helper Classes and Helper Functions by SJFriedl
• Getting to Understand Hierarchical RBAC Scheme by daemons
• Understanding "Safe" Validation Rules by SJFriedl
• Understanding the view rendering flow by dckurushin
• Understanding "Assets" by SJFriedl
• Understanding Scenarios by l.jurgs

to be continued...

This article was created to encourage the writing of "Understanding" articles by Yii wiki contributors and quick guiding Yii wiki readers to this type of articles.
All articles are tagged by "understanding" tag to combine articles into "Understanding" series.
feel free to add new "Understanding" articles to the list.