Products Ads DoubleClick for Publishers API Google Publisher Tag Google Publisher Tag The Google Publisher Tag (GPT) is an ad tagging library for Google Ad Manager that can dynamically build ad requests. GPT takes key details such as ad unit name, ad size, and custom targeting, builds the request, and displays the ad on web pages. See GPT Reference and help center documentation. Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 3.0 License, and code samples are licensed under the Apache 2.0 License. For details, see our Site Policies. Java is a registered trademark of Oracle and/or its affiliates. Last updated October 16, 2018.