Computer scanners are used to scan images, including documents and photos. Simple computer scanners are flat bed---they just have a sheet of glass on which you can place the document or photograph to be scanned.
More elaborate scanners have flat beds and automatic document feeders (ADFs) that are good for scanning a stack of documents at one time. Problems with the scanners are related to poor images or to ADF failures including jams. Troubleshooting scanners can be accomplished by following some steps.