A standard ad unit is a predefined size or format for an online advertisement, as specified by industry standards or best practices. Standard ad units are often used in the context of digital advertising, and provide a way for advertisers and publishers to ensure that their ads are compatible with the ad slots or placements on a particular website or platform. Standard ad units are typically defined by the Interactive Advertising Bureau (IAB), and are used by advertisers, publishers, and ad networks to ensure that their ads are properly sized, formatted, and delivered to the intended audience. Standard ad units are typically based on common dimensions, such as 300x250 pixels or 728x90 pixels, and can be used for a wide range of ad formats, such as display ads, banner ads, or video ads. Standard ad units can help to improve the compatibility, performance, and effectiveness of online advertising, and can help to ensure that ads are delivered to the right audience, in the right format, at the right time.