If you are receiving managed promotion with Matcha, we request access to your Facebook pixel.
A Facebook pixel is a piece of JavaScript code for your website that allows you to measure, optimize and build audiences for Facebook ad campaigns. Put simply, it’s what Facebook uses to retarget audiences on its platform. For instance if you have placed the Facebook pixel on your website and a user visits your website, you may retarget that person with a dark post on Facebook through their ad platform.

You can also leverage the pixel to store the actions people take on your website to further target audiences.
For more information on how to create a Facebook Pixel see this article.