Here are a some links to great sites that can be used to footprint any website to find out what is driving it!

• http://builtwith.com/
• http://w3techs.com/sites

There are a bunch of others out there that purport to tell you things like what CMS a site is built on, but I have found that most of them provide very limited information, and often the information provided is just wrong! Here are a few:

• http://guess.scritch.org/ is one of the better ones
• http://www.whatcms.org/
• http://whatcmsisthis.com/
• http://onlinewebtool.com/cmsdetector.php

Let me know if you have any others to add to the lists.

Footprinting is an aspect of reconnaissance that involves passively or actively attempting to gain as much information about a target as possible before you even think about attempting any sort of scan against the target. This article gives a brief overview of some of the main concepts and approaches to footprinting... the "big picture" rather than the nitty-gritty of what tools are used for what purpose, etc.