Techniques and practices used to bring products, services, opinions, or causes to public notice for the purpose of persuading the public to respond in a certain way. Weekly newspapers in London first carried advertisements in the 17th century; by the 18th century such advertising was flourishing. The first advertising agencies were established in the 19th century to broker for space in newspapers, and by the early 20th century agencies were producing the advertising message itself, including copy and artwork. Most advertising promotes goods for sale, but similar methods are used in public service messages to promote causes, charities, or political candidates. In many countries, advertising is the most important source of income for the media through which it is conducted. In addition to newspapers, magazines, and broadcast media, advertising media include direct mail (seedirect-mail marketing), billboards and posters, transit advertising, the Internet, and promotional items such as matchbooks or calendars. Advertisers attempt to choose media that are favoured by the advertisers' target audience. See alsomarketing; merchandising.