The Multitouch Client Driver is a software component that enables multitouch functionality on devices with touchscreens or touchpads. It allows users to interact with the screen using multiple fingers simultaneously, supporting gestures like pinch-to-zoom, swipe, rotate, and others. This driver is typically used for devices with capacitive touchscreens (such as laptops, tablets, or all-in-one PCs) that support multitouch input.