Introducing xdebug: „This article is the first installment of a five-part series of articles covering xdebug, a free and open source swiss army knife tool for PHP developers. xdebug is a PHP extension created by Derick Rethans, one of the PHP core developers. This week, we will show you how to install xdebug and introduce you to some of the basic features. In the subsequent parts of this article series, we will have a closer look at one of xdebug’s main features, namely tracing, profiling, debugging, and code coverage.
(Via Zend Developer Zone.)