Tracking pixels have evolved from tiny, pixel-sized images on web pages for tracking purposes to include a broad range of HTML and JavaScript embedded in web sites (and email). Tracking pixels can be hidden from sight and can track and send all sorts of personal data such as how a user interacts with a web page including specific items a user has purchased or information users have typed within a form while on the site. Businesses often want to use them to track consumer behavior (pageviews, clicks, interactions with ads) and target ads to users who may be more likely to engage or purchase something based on that prior online behavior.

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FTC Office of Technology. (2023, March 16). Lurking Beneath the Surface: Hidden Impacts of Pixel Tracking. Tech@FTC. https://www.ftc.gov/policy/advocacy-research/tech-at-ftc/2023/03/lurking-beneath-surface-hidden-impacts-pixel-tracking