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Let's say you visit the website, which organizes swaps of crafts and other items among users of the site. (Full disclosure: is a side project of a former AppNexus engineer and his wife.) You type into your browser's address bar, and your browser starts downloading content from a server somewhere. But, as your page is loading, your browser also starts passing information and requests to other sites and servers, such as DoubleClick, Quantcast, Google Analytics, and others. (To those in the ad tech industry, when a browser sends these information and makes requests, it's known as "making calls" or "calling" servers.) How would you know this? And what are those calls for?


Below is a screenshot of a Firefox add-on called Tamper Data recording the activity on the page. You can see the Quantcast, Google, and AppNexus ad calls, and in the last line you can see the page retrieving its favicon favicon (a file containing one or more small icons) from some folder in the website's content management system.


For any website you visit, it's possible to see the HTML and JavaScript code that your browser executes, causing content to show up in your screen, and causing the first round of calls described above. For example, if you go to using Firefox, and right-click on the page, you'll see an option called "page source." This option shows the below (truncated) code. You'll notice the Quantcast pixel that Ghostery alerted us to above.

Charles Web Debugging Proxy

It's not always easy in web and Internet development to know where exactly something went wrong. Tools such as Charles Web Debugging Proxy acts as an intermediary between your web browser (such as Internet Explorer, Chrome, Safari) and the Internet. You can install it on your computer, and your web browser can then be configured to access the Internet through the Charles Web Debugging Proxy. This is useful because it records all of the data that is sent and received, making it easier to know exactly what is happening, especially when trying to diagnose and troubleshoot an issue.


When you have an understanding of the available tools and background processes that browsers incorporate to monitor, track, and report on ad serving activity – it allows you to better select the appropriate tools and methods for your specific need. This ultimately equates into to improved ad targeting and increased revenue.