A DVD formatted for the NTSC market. Prior to digital television, NTSC and PAL were the two major analog TV formats, each with different frame rates and lines of resolution. When DVDs were introduced in the late 1990s, the media and DVD players had to accommodate the same frame and line specifications of the TV sets in their respective countries, which were still analog. NTSC DVDs can also be played in DVD players made for the PAL market; however, PAL DVDs cannot be played in NTSC DVD players. PAL DVDs can be converted to the NTSC DVD format, although it often requires technical prowess and patience. NTSC DVDs and PAL DVDs are defined as standard definition (SD) media (see DTV). See NTSC.