This document provides instructions for installing pixel tracking code on web pages to enable retargeting advertising campaigns. It explains that tagging code is a single line of HTML code that will anonymously tag visitors so they can be retargeted on other sites. The tagging code should be placed immediately after the opening <body> tag on pages, or in an include file. Placement is important to avoid disrupting other page elements. The document provides sample code and instructions for validating proper installation.