An ad agency, also known as an advertising agency, is a company that creates advertisements and marketing campaigns for clients. There are several other terms that can be used to refer to ad agencies, including marketing agency, creative agency, branding agency, and communication agency. These terms reflect different aspects of the services provided by ad agencies. A marketing agency may specialize in market research and strategy development, while a creative agency may focus on the visual and artistic aspects of advertising. A branding agency may help clients develop a unique brand identity, while a communication agency may specialize in public relations and media outreach. Ultimately, all these terms refer to companies that help clients promote their products or services through effective advertising and marketing.