Facebook allows you to create a “custom audience” by uploading a list of email addresses or phone numbers. Facebook will then hash (encrypt) the information and match it against their database. If users information matches those that you provided, you will then have your custom audience. Most marketers will use their email marketing lists to be able to serve ads to subscribers that match Facebook accounts and serve ads to them.
You can then amplify your reach by creating a “lookalike audience” from your custom audience. I know that sounds confusing, but to put it another way, you can target Facebook users that have similar traits to those from your custom audience. Facebook will find users that have similar data to those that are in your custom audience.
To begin, you would just need to go to this page and click on “create and audience” From there you can choose your custom audience and then determine the audience size. Keep in mind that the smaller the audience, the better matched they will be. A larger audience increases your potential reach, but reduces the similarities form your source list.
First up in setting up your lookalike audience is similarity. Facebook will help you target the top 1% of people on their network in the country that you select and who are similar to your current audience.
After that you will need to optimize your reach by finding the top 10% of people on Facebook in your selected country who are similar to your source audience.
You can then create your ad and further customize and target your audience. Facebook ads are a great way to reach a highly targeted audience that has a good potential to convert!