A flyer or flier, also called a circular, handbill or leaflet, is a form of paper advertisemen intended for wide distribution and typically posted or distributed in a public place or through the mail. Flyers may be used by individuals, businesses, or organizations to:

Promote a good or service, such as a restaurant or nightclub. Persuade or send a social, religious, or political message, as in evangelism or political campaign activities on behalf of a political party or candidate. Flyers have been used in armed conflict: for example, airborne leaflet propaganda has been a tactic of psychological warfare. Advertise an event such as a music concert, nightclub appearance, festival, or political rally Like postcards, pamphlets and small posters, flyers are a low-cost form of mass marketing or communication. There are many different flyer formats. Some examples are:

A4 (roughly letterhead size)
A5 (roughly half letterhead size)
DL (compliments slip size)