Advertising is a form of communication that typically attempts to persuade potential customers to purchase or to consume more of a particular brand of product or service. Modern advertising developed with the rise of mass production in the late 19th and early 20th centuries.

Many advertisements are designed to generate increased consumption of those products and services through the creation and reinvention of the "brand image" . For these purposes, advertisements sometimes embed their persuasive message with factual information. Every major medium is used to deliver these messages, including television, radio, cinema, magazines, newspapers, video games, the Internet, carrier bags and billboards. Advertising is often placed by an advertising agency on behalf of a company or other organization.

Organizations that frequently spend large sums of money on advertising that sells what is not, strictly speaking, a product or service include political parties, interest groups, religious organizations, and military recruiters. Non-profit organizations are not typical advertising clients, and may rely on free modes of persuasion, such as public service announcements.

Money spent on advertising has increased dramatically in recent years. In 2007, spending on advertising has been estimated at over $150 billion in the United States and $385 billion worldwide, and the latter to exceed $450 billion 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. In addition, advertising frequently utilizes psychological pressure (for example, appealing to feelings of inadequacy) on the intended consumer, which may be harmful.