What we call "high-definition television" encompasses both TV programming and hardware capable of rendering images--and sound--in far greater detail than we've been able to enjoy in our homes until quite recently. HDTV is the fruit of years of research in digital technology, and it's no exaggeration to call it the biggest advance in television and video since the shift from black-and-white to color. To enjoy HDTV, you first need a television or monitor (a display device with no tuner) capable of displaying a high-def image, and then you need one or more of the following:

• A digital TV (DTV) tuner capable of receiving free HDTV broadcasts (either a stand-alone or one that's integrated with the TV)
• Digital cable (check to make sure it's available in your area and that your provider transmits HD programming)
• Digital satellite service (if it's available in your area and your provider transmits HD programming)

Terms to Know
Interlaced: With an interlaced video output (VCR, video upscaler), a TV will render the horizontal lines in two separate passes 60 times a second: first the odd lines and then the even. You see true 30-frames-per-second video, but the constant toggling between even and odd lines results in slight flickering and other artifacts.

Progressive scanning: A method of image rendering in which all lines (even and odd) are drawn simultaneously and continually for a smooth, seamless image.

Image resolution: The baseline spec for HDTV is 720 horizontal lines or greater. Signal resolutions always specify whether they're interlaced or progressive: standard-definition NTSC broadcast TV is 480i (480 interlaced lines); digital HDTV signals are typically 720p (progressive), 1080i or 1080p.

Pixel resolution: Pixels are the smallest elements of a digital image. Pixel resolution refers to the number of pixels of an image, a video signal or a digital display. Amounts are listed as horizontal by vertical (for example: 1366 x 768).

ATSC/NTSC: The Advanced Television Standards Committee (ATSC) developed the digital television (DTV) standard adopted by the FCC in 1996. The National Television System Committee (NTSC) defined the standards for North American terrestrial broadcasting in 1953. An NTSC tuner receives standard-definition analog TV signals, while an ATSC tuner is optimized to receive a range of DTV signals.

Key Shopping Points
Besides your budget, the key things to consider when shopping for an HDTV are:

• Type of TV: LCD, Plasma, or Rear Projection? Where you want to put it may have the biggest effect on your choice, but it'll also come down to a balance of size, quality and features.
• Inputs: Composite, S-Video, Component or HDMI? Antennas, set-top boxes, AV receivers and other gear require different input connections.
• Programming: Will you watch mostly HDTV or DVD movies?

High-definition TVs and displays also pack incredible features, including some or all of the following:

• Widescreen image dimension (16:9 aspect ratio)
• Built-in ATSC/DTV tuner for free off-air HDTV reception
• PIP/POP (picture-in-picture/picture-outside-picture)
• PC input
• A digital interface for set-top receiver hookup (DVI, HDMI)

The main types are:

• LCD: Equally suitable for home theater and computer use. These screens filter light and color through tiny liquid crystals to create vivid images on glass surfaces. While not as high in contrast as plasma screens, they're less susceptible to burn-in (a condition where frequently viewed images like station icons leave permanent "ghosts" in the screen)--and entry-level LCD prices are plummeting.
• Plasma: Best for home theater use. Plasma screens use electrically charged, gas-filled cells to produce images of stunning vividness with an unparalleled color range. LCD's recent leaps have narrowed the quality gap between the two, but plasmas are getting bigger and better, too. Hardcore videophiles take note.

• DLP: Digital Light Processing technology, developed by Texas Instruments, is built around an optical semiconductor known as a Digital Micromirror Device, or DMD chip. Within the chip, microscopic mirrors mounted on tiny hinges tilt toward the light source (on) or away from it (off) in response to a video signal, thereby creating light or dark pixels on a projection surface. Not as slender as an LCD or plasma set, DLP sets are nevertheless far less bulky than CRT projection sets and sport far better images.
• LCD: Projection LCD TVs offer the chief benefit of a CRT projection screen--large screen size--along with the high brightness associated with flat-panel LCDs. While they're not as bulky as CRT projection sets, their images are not as sharp as most flat-panel LCDs. But they're also more affordable, inch for inch, than flat panels.
• HD-ILA: Also referred to as LCoS (Liquid-Crystal on Silicon), HD-ILA sets essentially combine LCD and DLP technologies to create large-screen rear-projection sets of unparalleled quality (deeper blacks than LCD sets) and remarkably shallow depth (though still thicker than a flat-panel set).

• LCD and DLP: Free-standing LCD/DLP projectors deliver high-quality images to projection screens of your choosing. The distance from the projection surface will determine your image size, and most projectors are light enough to reposition or transport with ease. Choose a front projector if you want the option to upgrade to a larger screen without replacing the guts of your hardware. It's also the easiest and the cheapest way to get a huge in-home image, being scalable from around 40 to 400 inches.