It's also a good idea to understand the following terms before you buy:
Batch scan: Allows multiple jobs to be performed simultaneously.
Bit depth: A bit is the unit of data that makes up the pixels, and in scanners, the bits contain colors. The greater the bit depth, the greater the variety of colors reproduced.
OCR: Identifies the numeric digits and alphabetic letters in scanned images and converts them into text characters so they can be changed and edited.
SCSI (Small Computer System Interface) card: The card is usually provided free with a SCSI scanner and slips into one of your PC's expansion slots. Macs have built-in SCSI connectors, but the iMac has a dedicated USB port. Most PCs using Windows programs require the card.
Single-pass/dual-pass: Single-pass scanning means the scanner only needs to take one look at the image before importing it to your PC. Some scanners require two or even three passes of a document in order to transfer primary colors. While a single pass seems like it may save more time, the density and detail of the image you're scanning may require additional time to be copied accurately.
TWAIN: A driver, or software, interface standard for acquiring graphics. Nearly all scanners come with TWAIN, making them compatible with those software programs that support TWAIN-compliant devices.
InfoTrends Research, http://www.infotrends-rgi.com