- Automatic Document Feeder.
An ADF is an automatic document feeder. It is part of a scanner (or copier) which allows automatic feeding of documents (or specifically of sheets). An ADF therefore makes scanning of multiple documents much easier because these do not need to be manually loaded one at a time but instead loaded into a scanner and left while the scanner scans loads and scans each in turn.
For more information see:
- http://everything.explained.at/Automatic_Document_Feeder/ - Automatic Document Feeder explained.