An advertising agency is a firm that provides advertising services to clients in order to create awareness and market their products. The key functions of an advertising agency include attracting clients, managing client accounts, developing creative advertising campaigns, conducting market research, planning media strategies, preparing advertising budgets, coordinating between clients and media/distributors, performing sales promotion, handling public relations, and providing additional non-advertising services like price-fixing and product/package design. Advertising agencies employ specialized teams to handle each function, such as account managers, creative teams, researchers, and media planners.