When someone visits your site and takes an action (filling out a lead form or completing a purchase), the Facebook pixel is triggered and collects this data. If a user is logged in to their Facebook profile at the time of this action, this action is tracked back to their specific user ID. This data can be used in a variety of ways:
Audience Building: Regardless of whether or not a user landed on your site or took an action as a result of a Facebook ad, users are added into audience buckets that you get to define. For example, if you want an audience defined by “any user who has added a specific product to their cart, but didn’t purchase it” – you can do that! If you want an audience defined by “the top 25% of users spending time on your site” – you can do that! If you only want “users who visited one section of your site, but not another” – you can do that too! You can set up a wide array of audience rules as long as the pixel is applied to your entire set with events defined. In addition, you can create “lookalike audiences” to reach additional users who are similar to your existing user base.
Conversion Tracking and Optimization: Once any user takes an action on your site, Facebook attempts to match that action back to a specific user ID, assuming that user is logged in to their Facebook profile. After matching an action to a user, Facebook is able to determine if that user was ever delivered an impression or clicked on an ad that you’re running. Depending on your attribution window, Facebook can attribute conversions to specific audiences and ads running within your campaign. This allows you to track and optimize delivery of your ads to users who are most likely to take an action and better understand what audiences and types of creative are performing for you.
Cross-Device Conversions: Unlike cookie technology, the Facebook pixel is people-based, meaning a user could see and click on an ad on their mobile device and later convert on their desktop and Facebook would still be able to attribute that conversion back to your ad campaign. There is not data loss between devices, assuming a user is perpetually logged in across their devices.
Analytics and Insights: Installing the Facebook pixel and corresponding events allows you to get rich insights about traffic on your site and actions users are taking from your pixel analytics dashboard. You can build journeys based on specific actions (e.g., site visit > product view > add to cart > purchase), or track lifetime value of customers.