While all scanners are designed for the same purpose - creating a digital reproduction of an image or document - scanners come in a variety of shapes and sizes designed to perform different types of tasks. Before worrying about technical specs or reproduction abilities, your first consideration should be what type of scanner best suits your needs. Here is a brief rundown of the three major types of office scanners and the functions they serve.

Flatbed
The easiest way to understand how a flatbed scanner operates is to imagine the top of a copier sliced off its base. Essentially, a flatbed scanner consists of its own base, with a flat piece of glass and cover just as is found on most copiers.

The scanning component of flatbeds runs over the length of the image in order to gather data. Flatbeds are particularly useful when a user needs to scan more than single page documents. Pages from a book, for example, can easily be scanned without having to copy each page individually first.

If you plan on scanning objects you'll want to focus on flatbeds. By placing a white sheet of paper over a bouquet of flowers a scanner can reproduce what appears to be a stock photo onscreen. Flatbeds do have a large footprint - they take up a lot of desk - so if space is a concern you may want to consider a different type.

Sheetfed
If you know that you won't be using your scanner for anything other than sheets of paper, a sheetfed scanner may be your best bet. Unlike flatbeds, the scanning component of sheetfeds is stationary while the document being scanned passes over it's 'eyes' - much like a fax machine. Usually only a couple of inches deep, a sheetfed scanner can easily fit between a keyboard and monitor.

Sheetfeds usually work best in conjunction with an automatic document feeder for large projects. While pictures and other documents smaller than a full page can be scanned using a sheetfed scanner, a flatbed is usually a better option for such tasks. Sheetfeds have been known to bend pictures and reproduce less than quality images.

Slide
Slides, because of the resolution needed to accurately reproduce very small images, do not work well in conjunction with flatbed scanners and an entirely different scanner market has been created as a result. Slides are usually inserted into a tray, much like a CD tray on your computer, and scanned internally.

Most slide scanners can only scan slides, though some newer models can also handle negative strips. If you plan to occasionally scan slides as well as other documents, some flatbed scanners have a magnified portion of their glass plate for scanning slides.