When a user lands on the offer URL, the tracker places a cookie file in the user's browser with a unique click ID of a tracker in it. By making a conversion, a user must get on the "Thank you" page on which it is necessary to place a pixel. After landing on this page, the pixel pulls up a unique click ID from the user's cookie and brings it back to the tracker. For an accurate tracking, the domain of a URL in the pixel should match the domain of a campaign URL, because the cookie is placed exactly on a domain.
How does tracker work by means of pixels?