A mimeograph is a duplicating machine that was widely used in the 20th century for producing copies of documents. It works by applying ink to a stencil, which is then pressed against paper to create multiple copies. This method was popular in schools, offices, and small businesses before the advent of modern photocopiers and printers. The mimeograph was invented in the late 19th century and became a staple for producing newsletters, flyers, and other printed materials. It allowed for quick and cost-effective reproduction, making it an essential tool for educators and community organizations, especially before the rise of digital printing technologies.