Click "View source" at the top right of most pages to learn by example.
The WebCore and all applications are fully documented with PHPDocumentor*.
Every class, property, method and variable is marked up with JavaDoc-style tags.
The documentation is in front of you as you browse the code and JavaDoc-aware editors
can generate code-completion information and in-place help while you work.
Source code is syntax-highlighted and linked with the documentation.
All applications are documented too, so you can use them as examples.
The WebCore API is separated into lite and full versions.
Lite (public API only)
Provides a clear picture of what the WebCore does, rather than how it does it.
Includes only the higher-level API, leaving off implementation details, such as
internal functions and classes.
 
Full (developer API)
Good for developing a new application or heavily customizing an existing one.
Includes absolutely every last little implementation detail: almost everything is documented
to some degree.
Shows you all of the aggravation the WebCore is sparing you!
 
*I highly recommend PHPDoc (not least because I spent some time
extending it just so it could handle the WebCore!).