Meta Pixel enables you to remarket to potential customers that have previously been on your site but abandoned their cart.

Cart abandonment is when site visitors place items in their shopping cart but don’t checkout. You can use Meta Pixel data to run highly targeted cart abandonment ads just to cart abandoners (low-hanging fruit) and hopefully persuade them to convert.

By using a custom Pixel Facebook audience and enabling the “Exclude” option you can choose to exclude those who continued on to add their payment information. Then you can run an ad campaign just to this audience (common ads are along the lines of "Did you forget something"?).
 
If you have not created a pixel  -  
1. Go to Events Manager on Facebook.
2. Click Connect data sources and select Web.
3. Select Meta pixel and click Connect.
4. Add your pixel name.
5. Enter your website URL
 
Add this Pixel ID to your Website in Settings under Analytics
 

Then you will need to create a new Facebook audience (see below image) to create a list of cart abandoners. By including people who completed purchase behaviour right up to the cart page but did not actually complete a sale (i.e hit the ‘thank you’ or ‘checkout complete’ page), you now have a cart abandonment audience.

To create a Cart Abandonment Audience on Facebook
 
1. Go to the Audience Page
2. Click Create Audience  
3. Click on Custom Audience  
4. Create the Audience using the below criteria



5. Click Create Audience
6. You can create an Ad from here now, assigning it to the new audience of cart abandoners.