Pixel
01 Definition
Pixel meaning: A small piece of code that loads on a page to record user actions for advertising.
A tracking pixel is a snippet, often a tiny invisible image or JavaScript, that fires when a page or event loads and sends data back to an ad or analytics platform. It powers conversion tracking, retargeting, and audience building. Browser blocking and consent rules increasingly limit what pixels can collect.
Also called
Why it matters
How Pixel fits the work
Pixels are how advertisers connect ad clicks to later actions like purchases, making them the foundation of conversion measurement and retargeting on the open web.
In context
After adding the platform's pixel to the checkout page, the advertiser could see which ad clicks led to completed purchases within the attribution window.
Practical note
Client-side pixels can be blocked by browsers, extensions, or lost to page errors, so many advertisers now pair or replace them with server-side tracking for more complete data.