The concept is simple: advertisers provide a list of the email addresses of their customers and Facebook uses those email addresses to target ads to them if they’re on the service.

Advertisers can also target users of their mobile apps, or through a tracking pixel, individuals who have visited their website.

For some advertisers, Custom Audiences are the secret to their success with Facebook ads, so it’s no surprise that the world’s largest search engine, Google, may be looking to take a page from Facebook’s playbook as it seeks to maintain its online ad dominance.

According to the Wall Street Journal, Google is in discussions with advertisers about new targeting functionality that would function almost identically to Facebook Custom Audiences.

The Journal says that targeting would be applied to search results only, at least to start, and could launch as early as this year.

Google shouldn’t have any problems identifying large numbers of users to email addresses. It operates one of the most popular free email services, Gmail, and asks for secondary email addresses when users initially sign up.

It also operates other popular services that users can register for, such as YouTube and Google Maps. 

Intent FTW?

Custom Audiences-like targeting functionality could be a huge boon for Google and its advertisers, but an even more interesting possibility is that Google will also roll out the ability for advertisers to target lookalike audiences based on their custom audiences. According to the Journal, Google is considering this.

Facebook offers a Lookalike Audiences feature that allows advertisers to target users who are similar to their Custom Audiences, and many advertisers use it to great effect. According to a study by Adobe Media Optimizer, the use of Lookalike Audiences has led to a tripling of sales for some advertisers.

While in most cases Google won’t have the same kind of deep social data about its users that Facebook does to assemble lookalike audiences, it has something potentially just as interesting: the ability to infer user intent based on their searches. 

If Google can take the demographic information it does have about users, and add an intent layer on top of this that Facebook doesn’t have, it could differentiate its new offering from Facebook in a big way.