Flyposting (also known as wild posting or bill posting) is done by placing advertisements without permission. Generally these are photocopied posters distributed amongst a large public area where they might be seen by consumers. Bus stops, buildings, lampposts, benches, railings, and stair wells are all good examples of flyposting targets. The act of flyposting can be seen as illegal or legal depending on where advertisements are placed. Government, businesses, bands and even common citizens have used flyposting in some capacity over the decades all in an attempt to achieve different goals.

The government uses flyposting in order to gain maximum exposure for a missing person campaign, for propaganda, and for political campaigns. Some everyday uses of flyposting are for missing animals and garage sales. A band will often flypost for an album release or for an upcoming concert. Businesses will use flyposting to advertise products to a specific market. It is often seen as a good alternative to other forms of advertisement because of its cost effectiveness and its ability to gain immediate saturation over an area in the short term. Flyposting as a marketing strategy is specifically regarded as a form of guerrilla marketing because of the goal of maximum exposure, which is why flyposting mainly takes place in urban settings, such as large cities.
Recently this marketing strategy has been met with more and more criticism as it is seen as a sign of urban decay. As larger cities and urban areas try to increase their visual presence they also want to be seen as having a good quality of life. Thousands of small advertisements littered throughout the city can make it seem dirty, and the original marketers are not held responsible for clean-up. Instead it is the city who must fund clean-up of these large areas. Camden council, the local government in north London spends about £100,000 a year on clean-up, while businesses are making money off this form of advertisement. Large businesses can be fined if caught; to mitigate this risk they often outsource this sort of work to groups who specialize in this form of marketing.

With the rise of technology this form of advertisement has shifted focus to the internet. Although most sites are paid by the advertisers, similarities can be drawn between some forms of adware, which are more invasive but are used to achieve an effect similar to flyposting.