scanner

A scanner is usually a device that reads, checks, or captures information. You might think first of a machine that turns a paper photo or document into a digital file, but the word is used in several common ways. A barcode scanner reads the pattern on a product, a body or bag scanner checks what is inside, and a virus scanner looks through computer files for harmful software.

The idea behind the word is simple: it moves across something or checks it closely to find information. In some contexts, it can also mean a device that listens to radio signals, such as a police or weather scanner. Sometimes people use it in a loose or figurative way for a person who looks over things quickly and carefully, but the main meaning is still a machine or program that examines and collects information.

The word "scanner" usually refers to a device or program that examines something in order to read it, record it, or detect specific details. At its most familiar, it is a machine that copies a paper document or photo into a digital form. In shops, a barcode scanner reads printed codes so the system can identify an item and its price. In medicine and security, scanners use technologies such as X-rays or other waves to create images of what cannot be seen directly.

The word is also used in computing and electronics. A virus scanner checks files and systems for harmful software, and a radio scanner receives or searches through radio frequencies for transmissions. In all of these cases, the central idea is the same: the device moves across information, or searches through it, to find something useful.

Sometimes "scanner" is used more loosely for a person who quickly looks through material or checks a situation carefully, but that is a less common extension of the main meaning. Most of the time, the word points to a machine, tool, or software system built to inspect, read, or detect.