A while back it was discovered that some ISPs have taken to inserting ads into web pages you are viewing, these are ads from the ISP you are using (AND PAYING FOR) not ads from the content provider or site that you are viewing.
It seems some ISPs have bought a device from Fair Eagle, which is basically a spam box – it attempts to insert ads into all HTTP traffic that passes through it.
This is where the Web Integrity Checker from Washington University comes in.
The University of Washington security and privacy research group and ICSI have created a measurement infrastructure. By visiting our web page, you are helping out with our experiment. (Thank you!) In the process, we’ll help you figure out if some “party in the middle” (like your ISP) might be modifying your web content in flight. We also plan to share our overall results with the public.
Just by visiting this page, your web browser is participating in our experiment. We are detecting whether some “party in the middle” is modifying a set of test web pages, and the results of the tests are shown below. If you do not see a “change found” message below, then we did not detect any modifications to the test pages.
Details on how it works are at the bottom of the page.