In March 2009, we announced a beta test of interest-based advertising, which included remarketing and interest category marketing, to help you reach people on the Google Display Network who are most likely to be interested in your products and services.

Early results show that interest-based advertising is helping deliver better ads and offers for your potential customers, more effective campaigns for you, and higher returns for website publishers. Remarketing was recently launched to everyone, and interest category marketing has continued to grow.

To help you better reach your customers, and to give users more control over which ads they see, we're adding some new categories that will enable you to show ads that relate to demographic categories, such as age and gender. This works exactly the same way as interest category marketing works today - Google associates categories with a particular browser by looking at the types of Google Display Network sites visited and compares that information with aggregated survey data on site visitation. For example, if someone frequently visits sites that have a majority of female visitors, we may associate her browser's cookie with the “female” demographic category. With this information, you can choose to show more ads that are relevant to women as she browses sites across the Google Display Network, exactly the same way you can currently show ads related to other categories like sports or gardening.

As with interest categories, users may view and edit demographic categories or permanently opt out of receiving interest-based ads entirely with the Ads Preferences Manager. Because the interests and inferred demographics associated with a particular browser are based on recently visited sites on the Google Display Network, and not on user data, these categories may change over time. As one of a number of companies offering ads based on inferred interests and demographics, we remain committed to providing users the highest level of control and transparency.

We're still beta testing interest category marketing (including the new demographic categories), but will be working to help more advertisers run campaigns over time.