When used as a verb, scan means to look at a page or set of pages (or other information) quickly. When used in terms of computers, to scan means to detect which of the computer's ports or channels are open and which have devices connected to them. In imaging, to scan means to either produce an image (such as on a computer display or output substrate) or capture an image (as in a scanner), often by means of a beam of light or electrons. When used as a noun, scan refers to the movement of such light or electron beams in imaging or image capture. In scanning, scan also refers to a captured, digitized image.