In Latin, ad vertere means "to turn toward." The purpose of advertising may also be to reassure employees or shareholders that a company is viable or successful. Advertising messages are usually paid for by sponsors and viewed via various traditional media; including mass media such as newspaper, magazines, television commercial, radio advertisement, outdoor advertising or direct mail; or new media such as blogs, websites or text messages.
Commercial advertisers often seek to generate increased consumption of their products or services through "branding," which involves associating a product name or image with certain qualities in the minds of consumers. Non-commercial advertisers who spend money to advertise items other than a consumer product or service include political parties, interest groups, religious organizations and governmental agencies. Nonprofit organizations may rely on free modes of persuasion, such as a public service announcement (PSA).
Modern advertising was created with the innovative techniques introduced with tobacco advertising in the 1920s, most significantly with the campaigns of Edward Bernays, which is often considered the founder of modern, Madison Avenue advertising.
In 2010, spending on advertising was estimated at $142.5 billion in the United States and $467 billion worldwide 
Internationally, the largest ("big four") advertising conglomerates are Interpublic, Omnicom, Publicis, and WPP.Source: http://en.wikipedia.org/wiki/Advertising