This article for IDM provides an introduction to PHP and then quickly delves into the details of how PHP meets development challenges and the useful features that are employed on some of the most popular sites on the web.

This review by Paul Ferris of PHP 4 appeared on LinuxPlanet and explains why in the author's opinion version 4.0 is a vast improvement, which he backs up with benchmarks and test results.

This article that appeared at internet.com includes a general overview, a review of the architecture and functionality and finishes off with a list of pro's and con's about the language.

This article is a followup to the article Free Software Profile: PHP, which failed to highlight the key differences of PHP3 vs. PHP4, most notably, what has been added.