ADF, short for Automatic Document Feeder, is a feature of some scanners and multifunction printers that allows multiple pages of paper to be automatically fed into the scanner without the need for manual manipulation. This feature is very useful when large volumes of documents need to be scanned or copied, as it can greatly simplify and speed up the process. An ADF system usually consists of a feeder that holds a bundle of documents and a mechanical system that feeds the page into the scanner page by page. Some ADF systems also support automatic duplex scanning (duplex×), which allows both sides of a sheet to be scanned without having to manually turn it over.