Mobile billboard is the marketing practice of advertisement on the side of a truck or trailer that is typically mobile. Mobile billboards are a form of Out-Of-Home advertisement. Radio, static billboards, and mall/airport advertisement fall into the same category. Using a mobile billboard for advertisement is an advertisement niche called Mobile Outdoor advertisement.
Most mobile billboards are dedicated, customized trucks with large, but narrow, bodies for posting the advertisements. Some of these dedicated units offer features such as external sound systems, illumination, and hot/cold boxes for product sampling. This type of mobile billboard is the most popular among vendors, and the most capable in terms of gaining exposure and quick deployment.