Stoyan Stefanov is a Yahoo! web developer, Zend Certified Engineer, and book author. He talks regularly about JavaScript, PHP, and other web development topics at conferences and on his blog at www.phpied.com, and also runs a number of other sites, including JSPatterns.com—a site dedicated to exploring JavaScript patterns. Stoyan is the engineering lead of Yahoo!'s performance optimization tool YSlow, and contributes to other open-source projects such as Firebug and PEAR.

A "citizen of the world", Stoyan was born and raised in Bulgaria, but is also a Canadian citizen, and is currently residing in Los Angeles, California. In his rare offline moments, he enjoys playing the guitar and going to the Santa Monica beaches and pools with his family.