A house ad is a type of advertising that is used by a publisher to promote their own products or services, rather than those of a third party advertiser. House ads are typically displayed on the publisher's own website or app, and are used to promote the publisher's own content, such as articles, videos, or apps. House ads are often used by publishers to drive traffic and engagement to their own content, and to monetize their own inventory. House ads can also be used to test the performance of different ad formats or creative, or to promote special offers or events. House ads are an important part of a publisher's advertising strategy, as they can help to generate revenue and to increase brand awareness and loyalty among their audience.