Capture is the process or means of obtaining and storing external data, particularly images or sounds, for use at a later time. There are various ways in which this can be done; the best method depends on the application.
In biometric security systems, capture is the acquisition of, or the process of acquiring, an identifying characteristic such as a finger image, palm image, facial image, iris print, or voice print. (All but the last of these examples involves video data; the last involves audio data.) In order to capture the data, a transducer is employed that converts the actual image or sound into a digital file. The file is then stored. At a later time, it can be analyzed by a computer, or compared with other files in a database to verify identity or to provide authorization to enter a secured system.
Most serious computer users are familiar with the term screen capture. The intent of a screen capture is to store the image on a monitor or display exactly as it appears at a specific time. This can sometimes (but not always) be done by hitting the "print screen" key, in which case the image appears as a bitmap file in the clipboard. It can also be done by photographing the display screen with a digital camera external to the computer.