A thin, digital, wide-screen high-definition TV (HDTV). Most flat panel TVs are a self-contained unit with a tuner and speakers that can receive over-the-air broadcasts. Some models are only display screens and require decoded content from a source such as a set-top box or media player. Flat panel TVs may also accept various resolutions from a computer and perform as a monitor (see flat panel display). LCD and OLED LCD and OLED are the two primary technologies used in TV sets today. Although offering excellent viewing, plasma TVs are no longer made. LED TVs are actually LCD TVs with an LED backlight. See LED TV and OLED. HD Resolutions The common HDTV is 1080p (1,080 progressive scan lines); however, earlier, smaller sets were 720p. Although Blu-ray supports 1080p, TV and cable channels broadcast in the lower 720p and 1080i resolutions. It is often difficult to tell the difference, especially on smaller TV sets. 4K TVs with 2160p resolution have also become widely available (see 4K TV). For resolution details, see DTV, HDTV and progressive scan. Will You Watch Vintage Content? If you watch standard definition (SD) content such as DVDs, VHS tapes or old movies on cable that are not in high definition, all HDTVs are not the same. The TV upconverts SD content to the higher resolution and stretches the old square format (4:3) to the wider screen (16:9). Some sets do a better job than others. Showroom TVs are often playing a Blu-ray cartoon, because Blu-ray discs are high resolution, and cartoons have saturated, dazzling colors. If you have a penchant for vintage content, ask for an SD demo, if at all possible. Size Makes a Difference Whether HD or SD, an enormous amount of complex processing takes place, and the larger the screen, the more jagged edges, pixelation and other visual artifacts are noticeable. It takes a high-quality 65" TV to look as good as a low-end 32" set, and even more so with an 80" TV (see deinterlace, cadence correction and dynamic noise reduction). Wall Mounting Although all flat panel TVs can be wall mounted, models 40" and above require a strong support. The wall bracket must be bolted into the studs of sheetrock and plaster walls by an experienced installer. See HDTV display modes, upconvert, aspect ratio, Blu-ray, home theater and rear-projection TV.