Lookalike audiences are groups of users that the advertising system evaluates as similar to a source audience – for example existing customers, people who submitted an enquiry, or the most valuable subscribers. They serve to extend reach beyond remarketing once the company's own audience is exhausted. The quality of the result depends above all on the quality of the source: an audience built from all visitors will produce an average result, while a list of the most profitable customers a significantly better one. It is therefore recommended to build sources from narrowly defined groups of sufficient size. When uploading customer lists, a legal basis is required and this use must be disclosed, because it involves processing personal data for advertising purposes. It is also worth refreshing the audiences on an ongoing basis, since a list compiled a year ago may no longer correspond to the company's current customers.
See also: Customer lists in advertising, Remarketing, Ideal customer profile.
