A Facebook pixel is a unique 15 digit ID that can be embedded in your website that lets you measure, optimize and build audiences for your ad campaigns. It helps you measure the effectiveness of your advertising by understanding the actions people take on your website.
SOME KEY BENEFITS
- Build advertising and re-marketing audiences.
- Generate Lookalike audiences.
- Make sure your Facebook ads are being shown to the right person.
- Measure the results of your ads.
- Get Facebook to optimize for conversions
- Reach new and existing customers.
Refer to this META article for more info.