From Wikipedia:
Advertising is a form of communication used to encourage or persuade an audience (viewers, readers or listeners) to continue or take some new action. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common. 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 websites and text messages.
Advertising is usually done to promote certain brands of products or services and commonly compare these brands to their closest to competitors to differentiate themselves from them. Advertising typically uses slogans and brand's easily identifiable logo to create an impression on the subjects watching the ad. There is a whole research in Semiotics of how to make advertisements more appealing to the consumer.
