Tracking pixel

A tracking pixel is a tiny piece of page code (historically a 1×1 image, today usually a JavaScript snippet) that fires an HTTP request to a collection server when a page loads or an event happens. The request itself is the data: it carries the page URL, referrer, timestamp, identifiers, and an event payload like "Purchase, $89".

#A pixel sends; a cookie remembers

Pixels and cookies are constantly conflated, and they do opposite jobs. The pixel is the messenger: it transmits what just happened. The cookie is the memory: it stores an identifier so the next request can be recognized as the same visitor. Pixels typically set cookies to do their job across visits, which is where the confusion starts and where the constraints bite: browsers now cap how long script-set cookies live (Safari's ITP: seven days), trim referrers, and let blockers suppress the request entirely. A well-built pixel degrades gracefully under those limits; a badly built one silently reports a smaller world.

In practice: Buron ships its own first-party pixel, collecting on your domain into your warehouse: the anatomy above, operated as a product.

What a live pixel's request actually contains, what browsers strip from it, and where pixels go from here: Tracking pixels: how they work and where they're going. The best-known instance gets its own entry at Meta pixel, and the full conversion territory routes from Conversion tracking & signal quality.