Browse WordPress Source Code Online
Want to really dig deep into the inner workings of WordPress? Did you know that you can browse the source code online? Not only is it presented in a convenient web interface but it includes inline documentation so you can learn more about how WordPress works.
Spend a few afternoons a week reading through the source and you’ll really get a good handle on WordPress classes and functions and the files where they can be found. If you ever have a question about how a particular bit of code in the core works, you can always refer to the online source that contains the inline documentation.