This inheritance list is sorted roughly, but not completely, alphabetically:

[detail level 12]

CSite	Routing and error handling
CUpload	A file upload
CUtil	Static helper functions
▼CArrayAccess
CController	A controller
CRequest	The request
CResponse	The response
CSession	The session
CView	Renders a template with data
▼CRuntimeException
CHttpError	An HTTP error with a user friendly message