Google AdSense is a program that lets you display Google-sponsored advertisements on a website and earn income. To use AdSense, you must place a piece of HTML code on your site for each advertisement you wish to show. Besides the details needed to display an ad, this code also contains a website owner's AdSense account number, or publisher ID. You can use your Web browser to trace your AdSense account number or the publisher ID for any website owner.
Instructions:
1)Navigate to the website containing the AdSense advertisements you wish to trace using your Web browser.
2)Press "Ctrl" and "U" at the same time on your keyboard to view the site's HTML source code. This shortcut works in most modern Web browsers. You can also right-click on a page with your mouse and choose "View Source" from the menu that pops up in Microsoft Internet Explorer.
3)Press "Ctrl" and "F" on your keyboard to search through the HTML source code. Type "google_ad_client" without the quotes and press "Enter" on your keyboard. The AdSense advertisement code, which contains the owner's publisher ID, will display. Look to the right of the "google_ad_client" identifier to find the AdSense account number. It uses the format of "pub-" followed by a group of numbers. All advertisements created by the AdSense account owner use this publisher ID.
Tips and Warnings:
AdSense publisher IDs do not reveal any personal information about owners. Google uses them only to identify AdSense publishers.
Source - eHow
