Interlacing refers to one of the two methods commonly used to generate a video image on an electronic display screen (the other being progressive scan). The interlace technique was devised for displaying high-quality full-motion-video images on early CRT televisions at while using minimal bandwidth. Interlacing technique uses two fields to create a frame; one field contains all the odd lines in the image, the other contains all the even lines of the image. The two sets of fields are interleaved to create a full frame every second scan. For a given bandwidth and refresh rate, interlaced video will provide a higher spatial resolution than progressive scan.