Powder in printers is a term used to refer to TONER, which is a dry powdery substance used in laser printers and photocopiers. TONER is made up of plastic particles, carbon, and iron oxide, and is used to create images on paper. It is applied to the paper by a process called electrostatic printing, where an electric charge is used to attract the TONER particles to the paper. The TONER is then fused to the paper using heat, creating a permanent image.