A pin-up girl, also known as a pin-up model, is a model whose mass-produced pictures see wide appeal as popular culture. Pin-ups are intended for informal display, e.g. meant to be "pinned-up" on a wall. Pin-up girls may be glamour models, fashion models, or actresses.
These pictures are also known as cheesecake photos. The term pin-up may also refer to drawings, paintings, and other illustrations done in emulation of these photos (see the list of pin-up artists). The term was first attested to in English in 1941; however, the practice is documented back at least to the 1890s. The pin-up images could be cut out of magazines or newspapers, or be from postcard or chromo-lithographs, and so on. Such photos often appear on calendars, which are meant to be pinned up anyway. Later, posters of pin-up girls were mass-produced and became an instant hit. As social standards changed, male subjects also began to be featured in pin-ups.