Tracking pixel

Historically a 1×1 image, today usually a JavaScript snippet. 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

The two are constantly conflated and 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 is recognized as the same visitor. Pixels typically set cookies to work across visits, which is exactly where browsers now push back: script-set cookies capped at seven days on Safari, trimmed referrers, and blockers suppressing the request entirely.

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

What a live pixel's request contains and what browsers strip from it: Tracking pixels: how they work and where they're going. The best-known instance has its own entry: Meta pixel.