WordPress knowledge base
First Steps with WordPress: http://codex.wordpress.org/First_Steps_With_WordPress
Explanations on most common WordPress terms: http://en.support.wordpress.com/lexicon/
Best WordPress-related articles for Web Developers: http://net.tutsplus.com/articles/web-roundups/top-50-wordpress-tutorials/
WordPress Optimization: https://codex.wordpress.org/WordPress_Optimization
Last updated