The Facebook pixel is a piece of code that is placed on your website and lets us measure, optimize, and build audiences for your campaign. When a user visits your website and takes an action (ex. Making a purchase, submitting a form), the pixel is triggered and reports the action. This allows us to track when a customer completed an action after seeing your Facebook ad. This gives us the ability to reach this customer again by using a custom audience or create a lookalike audience based on users who have already converted.