What is the term for the company that pays for advertising space?

The term for the company that pays for advertising space is "advertiser." An advertiser is typically a brand or a business that seeks to promote its products or services through various forms of advertising, such as digital ads, billboards, or TV commercials. In the context of digital marketing, the advertiser is the entity that invests in ad placements to reach their target audience, ultimately aiming to drive sales, generate leads, or enhance brand awareness.

In contrast, the other options describe different roles within the advertising ecosystem. An ad server is a technology platform used to store and deliver advertisements. Creatives refer to the actual content or design of the ads themselves. An agency, on the other hand, is a company that provides services to advertisers, handling aspects of the advertising process such as strategy, creative development, and media buying. Therefore, while all these roles are important in the advertising environment, the advertiser is specifically the one who directly purchases advertising space.