A mode in which the video raster is scanned over the face of the CRT by the electron gun, tracing alternate scan lines in successive refresh cycles. The quality of interlaced video is lower than sequentially scanned (non-interlaced) video because only half of the lines are refreshed at a time and interlaced video scans at a lower rate than non-interlaced video allowing for the manufacture of less expensive video monitors. NTSC video (standard TV) uses interlace video. A display system where the even scan lines are refreshed in one vertical cycle (field), and the odd scan lines are refreshed in another vertical cycle. The advantage is that the bandwidth is roughly half that required for a non-interlaced system of the same resolution. This results in less costly hardware. It also may make it possible to display a resolution that would otherwise be impossible on given hardware, The disadvantage of an interlaced system is flicker, especially when displaying objects that are only a single scan line high.