An infomercial is a form of television commercial that resembles regular TV programming yet is intended to promote or sell a product, service or idea. It generally includes a toll-free telephone number or website. Most often used as a form of direct response television (DRTV), they are often program-length commercials (long-form infomercials), and are typically 28:30 or 58:30 minutes in length. Infomercials are also known as paid programming (or teleshopping in Europe). This phenomenon started in the United States, where infomercials were typically shown overnight (usually 1:00 a.m. to 6:00 a.m.), outside peak prime time hours for commercial broadcasters. Some television stations chose to air infomercials as an alternative to the former practice of signing off, while other channels air infomercials 24 hours a day. Some stations also choose to air infomercials during the daytime hours, mostly on weekends, to fill in for unscheduled network or syndicated programming. By 2009, most infomercial spending in the U.S. occurred outside of the traditional overnight hours. Stations in most countries around the world have instituted similar media structures. The infomercial industry is worth over $200 billion.

The Washington DC-based National Infomercial Marketing Association was formed in late 1990; by 1993 "it had more than 200" members committed to standards "with teeth".

While the term "infomercial" was originally applied only to television advertising, it is now sometimes used to refer to any presentation (often on video) which presents a significant amount of information in an actual, or perceived, attempt to promote a point of view. When used this way, the term may be meant to carry an implication that the party making the communication or political speech is exaggerating truths or hiding important facts.

The New York Times cited a professional in the field as saying that "infomercial companies tend to do well during recessions."