TWAIN defines a standard software protocol and API (application programming interface) for communication between software applications and image acquisition devices (the source of the data). The three key elements in TWAIN are: • Application software An application must be modified to use TWAIN. • Source Manager software This software manages the interactions between the application and the Source. This code is provided in the TWAIN Developer’s Toolkit and should be shipped for free with each TWAIN application and Source. • Sou rce software This software controls the image acquisition device and is written by the device developer to comply with TWAIN specifications. Traditional device drivers are now included with the Source software and do not need to be shipped by applications.