Multi-touch is a method of interacting with a computer screen or smartphone. Instead of using a mouse or stylus pen, multi-touch allows the user to interact with the device by placing two or more fingers directly onto the surface of the screen. The movement of the fingers across the screen creates gestures, which send commands to the device. The term multi-touch is a trademark of Apple Inc. Multi-touch has been implemented in several different ways, depending on the size and type of interface. Both touchtables and touch walls project an image through acrylic or glass, and then backlight the image with LED's. When a finger or an object touches the surface, causing the light to scatter, the reflection is caught with sensors or cameras that send the data to software which dictates response to the touch, depending on the type of reflection measured