Pixel (Tag)

A pixel, or tag, is a small snippet of code on your site that reports back when a visitor does something, like viewing a page or buying.

You paste the pixel once into your site's code, and from then on it quietly fires every time someone loads a page or takes an action you told it to watch. When it fires, it sends a little message back to the platform: this person viewed a product, this person checked out, this person spent 4 minutes reading.

Say you run a Meta pixel. Someone lands on your product page, and the pixel sends a "ViewContent" signal to Meta. They buy, and it sends a "Purchase" signal with the order value. Meta uses those signals to show your ads to more people who behave like your buyers, and to tell you which ad drove the sale.

The catch is that a browser-side pixel misses more than it used to. Ad blockers, iOS privacy settings, and script failures mean a chunk of your events never arrive, which is why platforms now push you to pair the pixel with a server-side feed like the Conversions API so the important events still get through.

No pixel, no proof your ads did anything.