Pixel tracking records and tracks visitors as they move from one page to another. This let’s you know what visitors went from a specific page to another specific page. Pixel tracking is widely used in conversion tracking.
For example, you may want to know how many visitors view your one time offer (OTO) and then actually purchase it. You would place pixel tracking code on both your OTO sales page and your OTO thank you for your purchase page. This way you know the number of unique visitors to your OTO sales page and the number of unique visitors that view your thank you for your purchase page. This helps with calculating the number of visitors that converted into sales.