A scanner digitizes images or text documents and allows them to be transfered electronically. The key elements of a scanner are the optical resolution, scanning bed size, speed, and connectivity. The higher the optical resolution the less memory is need to store a higher quality picture. Scanners also have an enhanced resolution feature which stores a larger virtual copy of the image. Scanning bed sizes and scanning speeds vary with each machine. Scanners can be connected using SCSI, FireWire, USB (Universal Serial Bus), or Parallel.