Advertising aims to persuade audiences by appealing to their needs, hopes, and dreams to more effectively sell products, services, and brands. There are four main types of advertising formats: product information, product image, lifestyle, and personalized. The advertising industry employs over 21,500 people in the UK, with most working in creative roles and a quarter in media subsectors. Major London-based advertising agencies include Dare, DDB London, Grey London, and AMV BBDO, with DDB London owned by Omnicom Group following the 1986 merger of Doyle Dane Bernbach and BBDO.