For many of us it is important as well as interesting to see where our customers go, which pages they visit. Tracking the pages is quite simple with Google Analytics. However the question is: "How do you track the pages that do not exist?"
If you configure your server or web application to handle 404 error - page not found (I strongly recommend you do) you will have a template page that is displayed every time the user navigates to an invalid URL - a page that does not exist.
So, how do we do this? How do we track our customers that somehow got lost and landed in a location that does not exists, at least not as a valid location that would provide them with the information that they expected.
It's quite easy. If you search for more information you may come across Google Analytics blog post Tracking 404 Pages, which is now outdated as the new ga script is recommended instead of old urchin. The best source for the answer is Google documentation itself. Simply follow these instructions.
var pageTracker = _gat._getTracker("UA-xxxxx-x");
pageTracker._trackPageview("/404.html?page=" + document.location.pathname + document.location.search + "&from=" + document.referrer);
This code sends a virtual pageview of "/404.html?page=[pagename.html?queryparameter]&from=[referrer]" to your account, where [pagename.html?queryparameters] is the missing page name and referrer is the page URL from where the user reached the 404 page.
Then simply look for /404.html in your Top Content report.