Using one of the oldest tracking mechanisms in the book, some 77.4% of websites track users as they navigate around the web. The widely used mechanism for much of this tracking is an image file of a single pixel. There are, of course, more complex trackers that provide publishers and advertisers with data on page views.
The most prevalent tracker is Alphabet Inc. (NASDAQ: GOOGL) and Google, which uses trackers on nearly half (46.5%) of the website’s pages examined by researchers at Ghostery and Cliqz, according to a report in eMarketer. Facebook Inc. (NASDAQ: FB) tracks more than a fifth (21.9%) of its Facebook Connect pages. Together these two firms account for about three-quarters of the digital advertising market.
The Ghostery and Cliqz researchers examined 144 million web pages and found that 43.6% of global websites use two to nine third-party trackers. Just over a sixth (16.2%) use 10 or more trackers. Another sixth (17.6%) employ one tracker. Just under a quarter (22.6%) use no trackers at all.
The rise of trackers and high-frequency ad rates have resulted in more web users adopting ad blocking software. eMarketer estimates that by the end of this year just over 30% of web users will employ ad blocking software, nearly double the total (15.7%) who used the software in 2014.
For web users who care about protecting their privacy, ad blockers not only prevent them from seeing unwanted ads, but the blockers also prevent tracking scripts and single-pixel images from being downloaded.
For content publishers and advertisers, growing use of trackers is a double-edged sword, according to eMarketer:
[T]racking technologies allow for both segment targeting and retargeting. But the overuse of such marketing techniques has the potential to backfire on advertisers if audiences end a browsing session with concerns that companies are gathering too much data on them.
The more information on user behavior that sites try to collect, the more the sites drive adoption of blockers that prevent gathering any user data at all. Some trackers even degrade a website’s performance, and that can drive users to a competitor’s site.