List the names of any four input devices of a Computing System. Briefly describe about Optical Character Recognition (OCR).

Input Devices of a Computer System Keyboard Mouse Trackball Scanner Bar Code Reader Optical Character Recognition Web Camera Digital Camera Camcorder Microphone Joystick Optical Mark Reader Touch Pen Touch pad Touch Screen Light pen Graphic digitizer Optical Character Recognition Optical Character Recognition (OCR), is the mechanical or electronic conversion of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used as a form of data entry from some sort of original paper data source, whether documents, sales receipts, mail, or any number of printed records. It is crucial to the computerization of printed texts so that they can be electronically searched, stored more compactly, displayed on-line, and used in machine processes such as machine translation, text-to speech and text mining.