To make an electronic comparison of a signal, pixel or data structure as described in the following definitions.
In optical technologies, to read a printed form a line at a time in order to convert images into bitmapped representations or convert characters into text. See OCR
In video, to move across a picture frame a line at a time, either to detect the image in an analog or digital camera, or to refresh a CRT display.
To search a data file sequentially for specific content.
To search an executable file for a particular pattern. See antivirus program
To sequentially search for peripheral devices attached to the computer.