The terms scan and scanning have several meanings:

• In telecommunication:
  • The term scan has the following meanings:
    1. To examine sequentially, part by part.
    2. To examine every reference in every entry in a file routinely as part of a retrieval scheme.
    3. In radar, one complete rotation of the interrogating antenna.
    4. In SONAR, to search 360° or a specific search sector by the use of phased array of transducers.
    5. To sweep, i.e., rotate, a beam about a point or about an axis.
  • The term scanning has the following meanings:
    1. In telecommunications systems, examination of traffic activity to determine whether further processing is required. Scanning is usually performed periodically.
    2. In television, facsimile, and picture transmission, the process of successively analyzing the colors and densities of the object according to a predetermined pattern.
    3. The process of tuning a device through a predetermined range of frequencies in prescribed increments and at prescribed times. Scanning may be performed at regular or random increments and intervals.
    4. In radar and radio direction-finding, the slewing of an antenna or radiation pattern for the purpose of probing in a different direction. In radar, scanning may be mechanical, using a rotary microwave joint to feed the antenna, or electronic, using a phased array of radiators, the radiated pattern (beam) of which depends on the relative phases of the signals fed to the individual radiators. In civilian air traffic control radar, scanning usually implies continuous rotation of the antenna or beam about a vertical axis. In military radars, scanning may occur about other than a vertical axis, and may not encompass a full 360°.
  • Source: from Federal Standard 1037C in support of MIL-STD-188
• In the semiconductor electronics testing industry, the term scan has the following meaning:
  • To test the logic used in an integrated circuit in a non-functional method by using a special test mode. This mode generally changes the configuration of the device being tested to look more similar to a large shift register. Logical blocks are then tested by loading and unloading this register. (See for instance JTAG Boundary Scan.)
• Scanning is also a term for the medical technique for body imaging.
• Scanning is also the term for the lowest-level work of a compiler, putting together the individual characters of the text of a computer program to form lexemes.

See also: scanner