What term describes an organization that plans marketing and advertising campaigns on behalf of clients?

The term that describes an organization that plans marketing and advertising campaigns on behalf of clients is "Agency." In the context of digital advertising, agencies specialize in developing strategies, creative content, and campaign management to help brands effectively reach their target audience. They often provide services such as media planning and buying, creative development, and performance analytics, leveraging their expertise to enhance the overall marketing efforts of their clients.

The role of an agency is critical, as they act as intermediaries between businesses looking to advertise and the various media platforms available for reaching consumers. Agencies not only create advertising strategies but also handle the execution of campaigns, such as designing ad creative, selecting distribution channels, and analyzing campaign performance to optimize results.

In contrast, other terms mentioned—like "Advertiser," "Publisher," and "Broker"—represent different components of the advertising ecosystem. Advertisers are the clients who pay for the advertising, publishers are the platforms or media outlets that display the ads, and brokers typically facilitate deals or transactions between buyers and sellers but do not primarily focus on campaign planning.