A banner is a graphical advertisement that appears on a website or app. Banners are typically rectangular in shape and are displayed prominently on a webpage or app to attract the attention of users. Banners can be static, meaning they don't change, or they can be animated, meaning they include movement or other interactive elements.

Banners are a common type of display ad, and are often used by advertisers to promote their products or services to a specific audience. Banners may be placed on a webpage or app using a variety of methods, including through direct deals with publishers, through ad networks, or through programmatic ad buying.

Banners are often designed to be eye-catching and engaging, and may include a variety of elements such as images, text, and call-to-action buttons. They may also include tracking codes or ad tags that allow advertisers and publishers to track the performance of the ad, including how many users have viewed the banner and how many have clicked on it.

When a user clicks on a banner ad, they are typically redirected to the advertiser's website or landing page, where they can learn more about the product or service being advertised. Banner ads are a common form of display advertising and can be effective at driving traffic and engagement to a website.