Form of communication

Advertising is a form of communication whose purpose is to inform potential customers about products and services and how to obtain and use them. Many advertisements are also designed to generate increased consumption of those products and services through the creation and reinforcement of brand image and brand loyalty. For these purposes advertisements often contain both factual information and persuasive messages. Every major medium is used to deliver these messages, including: television, radio, movies, magazines, newspapers, video games, the Internet (see Internet advertising), and billboards. Advertising is often placed by an advertising agency on behalf of a company.

Advertisements can also be seen on the seats of grocery carts, on the walls of an airport walkway, on the sides of buses, heard in telephone hold messages and in-store public address systems. Advertisements are usually placed anywhere an audience can easily and/or frequently access visuals and/or audio and print

Organizations which frequently spend large sums of money on advertising but do not strictly sell a product or service to the general public include: political parties, interest groups, religion-supporting organizations, and militaries looking for new recruits. Additionally, some non-profit organizations are not typical advertising clients and rely upon free channels, such as public service announcements.

Advertising spending has increased dramatically in recent years. In the United States alone in 2006, spending on advertising reached $155 billion, reported TNS Media Intelligence. That same year, according to a report titled Global Entertainment and Media Outlook: 2006-2010 issued by global accounting firm PricewaterhouseCoopers, worldwide advertising spending was $385 billion. The accounting firm's report projected worldwide advertisement spending to exceed half-a-trillion dollars by 2010.

While advertising can be seen as necessary for economic growth, it is not without social costs. Unsolicited Commercial Email and other forms of spam have become so prevalent as to have become a major nuisance to users of these services, as well as being a financial burden on internet service providers. Advertising is increasingly invading public spaces, such as schools, which some critics argue is a form of child exploitation.