O

OCR software
software which changes a scanned document from an image to editable text
operating system
the instructions that the computer uses to tell itself how it "operates". It's the answer to "Who am I and what can I do?"
optical codes
printed bar codes on products, envelopes, etc.
optical mark recognition
machine reads special marks, for example to score a test
optical character recognition
program that uses a machine to recognize the shapes of letters and characters. In the past special shapes had to be used that the computer could recognize. Modern OCR programs can recognize standard fonts very accurately.
optical disk
a storage medium which uses tiny lasers to create peaks and valleys in a plastic layer on a circular disk
optical card
embedded data on a card. May not be updatable.
orientation
direction the printed page runs: portrait or landscape
OS/2
an operating system by IBM
output
data that has been processed into useful form, now called Information