It used to be that the only way to track visitors was via web logs. No visitor can escape them. If they request a page or any content from your site, you have a log of it along with any information your server collected.
This usually meant maintaining software to analyse your logs, making sense of all that raw data, and rolling it up to meaningful trends and other higher level views.
Soon, though, analysing trends wasn’t enough. Businesses and marketers wanted to analyse what individual were doing, page by page, from one site to the next. They introduced third-party javascript libraries to track users on the web, learning who they were, and what they liked, ultimately selling that information.
They provided an incentive for websites to use their Javascript by eliminating the need to need to host their own analysis software, or keep it up-to-date. You begin using Google Analytics or Demand Base, and immediately have access via your browser to intelligence gathered from your site, and perhaps intelligence gathered from other sites. Certainly, this is too good to be true.
And it is. One problem is that it requires a user to enable Javascript for third-party sites. A third-party site is one other than the site they are currently visiting. Additionally, these third party sites were rarely needed for the site to work. So, if they were at asiteworthvisting.com, they only need to run Javascript that came from asiteworthvisiting.com in order for the site to work properly. They do not need to execute Javascript loaded from demandbase.com or google-analytics.com, two sites that try to use that Javascript to track visitors to sites; or, any other third-party site used for tracking.
One of the earliest and most popular Firefox plug-ins was the noscript plug-in. When installed, by default, it will usually permit Javascript to only be executed from the current site. The effect is that these third-party analysis sites had not record of them visiting any of the sites that used them to track.
The irony is that when I warn people who chose to use these third party vendors to track visitors that they would not see a good portion of Firefox users in their statistics, they’d respond that it doesn’t matter because most of their visitors are not using Firefox. I’d say, how do you know that. You can see where this is going. Firefox users with the noscript plug-in don’t appear in their data, so they are like stealth visitors that they never know about.
The thing is, despite the noscript plug-in being one of the most popular, it still requires a person to install it after installing Firefox. Not all Firefox users have the plug-in.
A new version of Firefox, however, will block third-party cookies by default. While this won’t hide all Firefox users because Javascript may still execute without the noscript plug-in, it does decrease their ability to store and use identifying information as people travel from one site to another.
In the end, log files are still the truest way to track visitors to your site. If you want intelligence about what your visitors do on other sites, or information gathered overall on those people, you can still leverage these third party marketers. However, the quality, detail and quantity of information they will have will decrease as browsers increase user privacy. Yet, because this will not happen in a uniform way across all browser vendors, you’ll want to be careful about your browser statistics or assumptions about the totals in your data if you are relying on these third-party Javascript and cookie based solutions.
