The following content is directly from Facebook.

If you already set up your Meta Pixel using IMG tags or plan to do so, we recommend that you follow our developer documentation. Learn more.

The Meta Pixel is a piece of code that you put on your website that allows you to measure the effectiveness of your advertising by understanding the actions people take on your website.

You can use the Meta Pixel to:

• Make sure your ads are shown to the right people. Find new customers, or people who have visited a specific page or taken a desired action on your website.
• Drive more sales. Set up automatic bidding to reach people who are more likely to take an action you care about, like making a purchase.
• Measure the results of your ads. Better understand the impact of your ads by measuring what happens when people see them.

Once you’ve set up the Meta Pixel, the Pixel will log when someone takes an action on your website. Examples of actions include adding an item to their shopping cart or making a purchase. The Meta Pixel receives these actions, or events, which you can view on your Meta Pixel page in Events Manager. From there, you’ll be able to see the actions that your customers take. You’ll also have options to reach those customers again through future Facebook ads.

If you use the Pixel to share events with Meta, we recommend that you also use the Conversions API. The Conversions API works with your Pixel to help improve the performance and measurement of your Facebook ad campaigns. Learn more about the Conversions API.

Our Business Tools Terms require that businesses (or partners acting on their behalf) may not place Pixels associated with their Business Manager or ad account on websites that they do not own without our written permission. Starting May 5, 2021, we’ll show verified domain owners the events and custom conversions recently received from Meta Pixels placed on their website. While verified domain owners will see all these events, the only events they can use for ad optimization and reporting are events they can access from their own Business Manager Account. If you don’t want your Meta Pixel or custom conversion information visible to the domain owner, you can remove the Pixel from the website or delete the custom conversion before the specified date.

Note: Apple’s iOS 14.5 changes require apps in the App Store that engage in what Apple defines as “tracking” to show a prompt to iOS 14.5 and later users in accordance with their AppTrackingTransparency framework. These changes impact how Meta receives and processes events from tools like the Meta Pixel. If you optimize, target or report on web events from Meta Pixel or any of our other business tools, you can take steps to update your event setup and manage these changes. Learn more.