Online Advertising, or digital advertising, refers to the industry of marketing products, services, or messages through integrated advertisements on various forms of digital media. Adding to the long history of strategically placing advertisements in reserved spaces found in newspapers, magazines, billboards, and television commercials, online advertising similarly consists of organizing assorted sizes of advertisements effectively within webpage layouts.

Often referred to as banners, online ads should be designed to best use the standardized ad sizes that work well with a large range of website layouts. Websites are compensated by advertisers based on the number of views and clicks their advertisements receive.