HDTV basics
Updated February 13, 2009
Today the majority of televisions sold in the United States are HDTVs. In fact, we recommend you avoid buying any TV that's not high-def unless you're really strapped for cash. But while high-def is the norm, it's still fraught with potentially unfamiliar terms, concepts, and issues, so read on for details about the de facto television standard.
HDTV basics:
Analog, digital, and HDTV | HDTV tuners | HDTV resolutions |
Regular TV and DVD on an HDTV | Your HDTV tomorrow
Analog, digital, and HDTV
Analog: An analog TV cannot display HDTV programming. It can show only standard-definition programs such as those found on regular TV, cable, or satellite channels--including digital cable and DirecTV or Dish Network.
Digital: The words "digital television" are used as a generic term for SDTV, EDTV, or HDTV.
SDTV: A standard-definition television is an analog television equipped with a built-in ATSC tuner (see below), which allows it to receive digital TV broadcasts. It will display a picture from these broadcasts, but HDTV shows won't look nearly as detailed as they would on a true HDTV.
EDTV: This stands for enhanced-definition TV, and usually it describes a television that can display HDTV signals but doesn't have enough resolution to really do them justice. Most often it applies to plasma TVs and denotes 852x480 pixels (more info).
HDTV: High-definition televisions, or HDTVs, can display standard TV, progressive-scan DVD, and HDTV signals. They're by far the most common type of digital television. Nearly every plasma, LCD, and rear-projection TV is an HDTV.
EDTV monitor or HDTV monitor: Describes a television that lacks a built-in tuner of any kind. These sets still work perfectly well with external tuners, including HD-compatible satellite and cable boxes.
HDTV tuners

Dish Network's DTVPal DVR is an external ATSC tuner with DVR.
Over the air: By law, almost all televisions sold after March 1, 2007, must include a built-in tuner (called HDTV, digital, or ATSC tuners) that can receive high-definition programs over the air by simply connecting an antenna. If your HDTV doesn't have such a tuner, you'll also need to connect an external tuner (or cable or satellite box) to watch high-definition programming. There's a loophole in the law, though: if the product contains no tuner whatsoever--for TVs, this means it's a "monitor"--then the mandate does not apply. As a result of the over-the-air tuner mandate, nearly all televisions sold after that date should be ready for the analog switch-off, aka the DTV transition.
DTV transition: Congress has passed a bill that requires over-the-air television stations to switch completely over to digital broadcasting sometime between February 17 and June 12, 2009. After the final June date, TVs and other gear with older NTSC tuners will be unable to receive over-the-air broadcasts. Anyone who watches TV via "rabbit ears" or a rooftop antenna (as opposed to cable or satellite), and whose TV does not have a built-in or separate digital tuner, will stop receiving programs on that TV. Because the switch-off of analog TV broadcasts would deprive many viewers of their only source of television, Congress also created a subsidy program. Run by the government's National Telecommunications and Information Administration (NTIA), the program will provide $40 coupons, limit of two per household, each of which can be used to pay for one digital converter box. . For more information, check out our Guide to the DTV Transition.
Cable and satellite: The FCC's plans for ATSC tuners and the DTV transition have nothing to do with HDTV over cable and satellite. Subscribers to these pay TV services can simply get a set-top box that tunes HDTV channels, plug it into their HDTV-ready sets, and watch HDTV. For more information, check out HDTV programming compared.
HDTV resolutions
Resolution, or picture detail, is the main reason why HDTV programs look so good. The standard-definition programming most of us watch today has at most 480 visible lines of detail, whereas HDTV has as many as 1,080. HDTV looks sharper and clearer than regular TV by a wide margin, especially on big-screen televisions. It commonly comes in three different resolutions, called 1080p, 1080i, and 720p. Comparing the latter two, 1080i has more lines and pixels than 720p, but 720p is a progressive-scan format that should deliver a smoother image that stays sharper during motion. 1080p combines the superior resolution of 1080i with the progressive-scan smoothness of 720p. True 1080p content is scarce outside of Blu-ray, some video-on-demand sources, and the latest video games, however, and none of the major networks has announced 1080p broadcasts. Despite the complexity of all these numbers, however, the simple fact is that all three HDTV resolutions look great compared with standard-def video, and it's quite difficult for anyone to tell the difference between the three. Check out our comparison chart to see how HDTV stacks up against standard TV and progressive-scan DVD, and go to HDTV resolution explained for more, um, detail.
| Name | Resolution | HDTV? | Wide-screen? | Progressive-scan? |
| 1080p | 1,920x1,080 | Y | Y | Y |
| 1080i | 1,920x1,080 | Y | Y | N |
| 480p | 852x480 | N | Y | Y |
| Regular TV | Up to 480 lines | N | N | N |
Regular TV and DVD on an HDTV
Regular TV on an HDTV: Many people bringing home an HDTV for the first time are disappointed by the picture they see. That's usually because they're watching a regular, standard-definition channel instead of an HDTV channel. Regular TV on an HDTV can look pretty bad, especially in comparison to high-definition programming. HDTVs are bigger and sharper than older standard-definition TVs, so they show off more of the flaws and relative softness of SD channels and content. Some HDTVs can improve lower-quality sources a bit more than others can, but in general there isn't much any HDTV can do to make standard-def TV programming look better.
DVD on an HDTV: HDTVs can make DVD, a very high-quality source, look spectacular, and most people are quite satisfied by the look of DVD on their HDTVs. Many DVD players and all Blu-ray players, also have built-in upconversion processing, which is supposedly designed to convert DVDs to high-definition resolution. In most cases, however, the benefits of this conversion process, if any, will be subtle.
Your HDTV tomorrow
If you buy an HDTV today, you can be fairly certain it won't become obsolete anytime in the next few years. Yes, new technologies come out every year, but nothing on the scale of the shift from standard-def to high-def TV will occur again for a good, long time. Nearly every current HDTV is equipped with a future-ready HDMI input, which assures compliance with tougher copy-protection standards, and as long as your new HDTV has one, you should be good to go.
Want more information on HDTV? Check out the introductory article HDTV 101: A beginner's guide, which is the gateway to the expanded suite of articles at CNET's HDTV World.