Look Alike Audience (LAA)
A Lookalike Audience is a way to reach new people who are likely to be interested in your business because they're similar to your best existing customers.
When you create a Lookalike Audience, you choose a source audience (a Custom Audience created with information pulled from your pixel, mobile app, or fans of your Page). The ad plateform identifies the common qualities of the people in it (for example, demographic information or interests). Then, they deliver your ad to an audience of people who are similar to (or "look like") them.