A stencil is a template used to draw or paint identical letters, numbers, symbols, shapes, or patterns every time it is used. Stencil technique in visual art is also referred to as pochoir. Stencils are formed by removing sections from template material in the form of text or an image. This creates what is essentially a physical negative. The template can then be used to create impressions of the stenciled image, by applying pigment on the surface of the template and through the removed sections, leaving a reproduction of the stencil on the underlying surface. Aerosol or painting stencils must remain contiguous after the image is removed, in order for the template to remain functional. Sections of the remaining template which are isolated inside removed parts of the image are called islands. All islands must be connected to other parts of the template with bridges, or additional sections of narrow template material which are not removed.
"Happy 1984" - Stencil graffiti found on the Berlin Wall in 2005. The object depicted is a DualShock video game controller.
Stencils are frequently used by official organizations, including the military, utility companies and governments, to quickly and clearly label objects, vehicles and locations. Stencils for official application can be customized, or purchased as individual letters, numbers and symbols. This allows the user to arrange words, phrases and other labels from one set of templates, unique to the item being labeled. When objects are labeled using a single template alphabet, it makes it easier to identify their affiliation or source.
Stencils have also become popular for graffiti, since stencil art using spray-paint can be produced quickly and easily. These qualities are important for graffiti artists where graffiti is illegal or quasi-legal, depending on the city and stenciling surface. The extensive lettering possible with stencils makes it especially attractive to political artists. For example, the anarcho-punk band Crass used stencils of anti-war, anarchist, feminist and anti-consumerist messages in a long-term graffiti campaign around the London Underground system and on advertising billboards. Also well known for their use of stencil art are Blek le Rat and Jef aerosol from France, British artist Banksy, New York artist John Fekner, world traveling artist Above, and Shepard Fairey's OBEY.