All of us nowadays visit and participate in social sites and networks. Practically a social network is a web site where users take action and not just read content. Digg.com and Facebook are perfect examples of such sites.

PHPizabi is an open-source script written in PHP (like the name shows) which is aimed to help developers create their own social site in fiew steps. As most of web apps (like WordPress), PHPizabi requires:

PHP 4.2.x or above
MySQL 3.23.x or above
Apache 1.13.19 or above OR IIS 5.1 or above
GD2 (Image Processor)

PHPizabi is built with security in mind: there are three administrative security layers and internal structure management, coupled with bruteforce protection. The app seems to be fast (though I have not tested it under heavy load). Modules (add ons) are supported, so developers can expand functionality and features with few clicks.

The end user experience seems to be complete, compared to famous social networks: customizable profiles, internal message sending (PMs), online-offline status, friend invitations, private photo gallery, smilies, comments and all the cool stuff used around. You can see a complete list of the features in the official PHPizabi web site. A demo installation can be found here.

In general PHPizabi seems to be a usefull platform for building social sites and is supported by an ongrowing community. If anyone uses PHPizabi and has tested it under heavy load, feel free to leave a comment and share your experience with us !