The switch to digital TV promises several benefits:

Viewers should notice improvements in picture and sound quality, particularly in the case of high-definition (HDTV) broadcasts. (To get the full effect, you’ll need a high-definition set, and the broadcaster and, if applicable, cable or satellite provider must provide a high-definition signal.)...

Standard Definition TV (SDTV)

SDTV is the basic level of quality display and resolution for both analog and digital. Transmission of SDTV may be in either the traditional (4:3) or widescreen (16:9) format. Digital SDTV provides pictures and sound comparable to the best available analog TV....

The difference between Analog TV and Digital TV boils down to the way the TV signal is transmitted. Standard analog TV is transmitted in a manner similar to radio.

In fact, the video signal of analog television is transmitted in AM, while the audio is transmitted in FM. Analog TV is subject to interference, such as ghosting and snow, depending on the distance and geographical location of the TV receiving the signal....

“DTV” is a general reference to Digital Television, as compared to “analog” Television. DTV broadcasts can be either HDTV (high-definition television) or SDTV (standard-definition television). HDTV can broadcast at resolutions typically as high as 1920 by 1080 pixels (2 million pixels), whereas the resolutions of SDTV broadcasts are typically only as high as 640 by 480 pixels (290,000 pixels).

In comparison, analog television produces a total of about 210,000 pixels. Broadcasters and cable providers can choose which format of DTV they transmit, and most DTV's and new HDTV set-top boxes will be able to receive the signal regardless of which format is transmitted. Note, however, that your standard analog TV set will not be able to receive DTV signals (neither HDTVnor SDTV). ...

If you receive only free over-the-air television programming, the type of TV you own, either a digital TV or an analog TV, is very important. Consumers who receive only free over-the-air television may view digital programming through a TV set with a built-in digital tuner (integrated DTV) or a digital-ready monitor with a separate digital tuner set-top box. (Both of these digital television types are referred to as a DTV). The only additional equipment required to view over-the-air digital programming with a DTV is a regular antenna, either on your roof or a smaller version on your TV such as “rabbit ears.”

If you have an analog television, you will have to purchase a digital-to-analog set-top converter box to attach to your TV set to be able to view over-the-air digital programming....

TVs connected to cable, satellite, or other pay services do not require a TV converter box from this program to receive programs after February 17, 2009. Check with your cable or satellite provider to determine how they will support your analog set after February 17, 2009. Time Warner, Comcast and Direct TV Cable are already broadcasting digital programming.

The cable companies have agreed to continue to furnish analog versions of the locally available over the air digital TV until 2012, or to furnish converter boxes. What they choose to do regarding any other analog TV they presently have, is up to them....