TWAIN

The TWAIN scan engine allows you to capture images from a scanner using TWAIN drivers. The TWAIN driver appropriate for the given scanner must be installed on your machine to use this scan source. This driver will be provided by your scanner's manufacturer if the scanner supports TWAIN.

For any given scanner, TWAIN is usually slower than ISIS, so if speed is a concern and ISIS is available, you may prefer to use ISIS/ScanConnect.