High-definition television (or HDTV, or just HD) refers to video having resolution substantially higher than traditional television systems (standard-definition TV, or SDTV, or SD). HD has one or two million pixels per frame, roughly five times that of SD. Early HDTV broadcasting used analog techniques, but today HDTV is digitally broadcast using video compression.

High-definition television in the United States was introduced in 1998 and has since become increasingly popular. Dozens of HD channels are available in millions of homes and businesses both terrestrially and via subscription services such as satellite, cable and IPTV. A November 2009 survey by Home Media Magazine found that between 33 and 50 percent of Americans have at least one HDTV in their home. Also, 66 percent said they subscribe to HDTV services

High definition versus standard or enhanced definition 

It is not clear whether broadcasting HDTV or multiple standard definition (SD) channels during non-primetime hours will become common. Many Public Broadcasting Service member stations are now carrying SD multicasts when not broadcasting in HDTV; but unlike many commercial stations, most of these multicasts are suspended while HDTV programs are being broadcast.
The prevailing expectation is that native HDTV (i.e., programming recorded with a digital HDTV camera) during primetime will predominate. The great majority of primetime television shows in the United States are available in HDTV at the network level. It is up to the affiliates, not all of which have HDTV broadcast capability, to retransmit these shows at HDTV resolutions. A number of non-primetime shows, including morning news shows and some soap operas, are also available in HDTV.

From proposals to introduction

The Federal Communications Commission (FCC) began soliciting proposals for a new television standard for the U.S. in the late 1980s and later decided to ask companies competing to create the standard to pool their resources and work together, forming what was known as the Grand Alliance in 1993.
On July 23, 1996, WRAL-TV (the CBS affiliate in Raleigh, North Carolina) became the first television station in the United States to broadcast a digital television signal.[2]
HDTV sets became available in the U.S. in 1998 and broadcasts began around November 1998. The first public HDTV broadcast was of the launch of the space shuttle Discovery and John Glenn's return to space; that broadcast was made possible in part by Harris Corporation.[3] The first major sporting event broadcast in HD was Super Bowl XXXIV on January 30, 2000.

Some HD TV List Guideline

Samsung UN55B8000 55-Inch 1080p 240 Hz LED HDTV
LG 32LD450 32-Inch 1080p 60Hz LCD HDTV
LG 32LH30 32-Inch 1080p LCD HDTV, Gloss Black
ViewSonic VT2430 24-Inch 1080p LCD HDTV
Samsung LN40B550 40-Inch 1080p LCD HDTV with Red Touch of Color
Samsung Touch Of Color T220HD 22-inch LCD HDTV Monitor
Panasonic VIERA X1 Series TC-L26X1 26-Inch 720p LCD HDTV
Samsung LN40C630 40-Inch 1080p 120 Hz LCD HDTV (Black)
Samsung LN46C630 46-Inch 1080p 120 Hz LCD HDTV (Black)
Samsung LN52B750 52-Inch 1080p 240 Hz LCD HDTV with Charcoal Grey Touch of ColorSharp LC19SB27UT 19-Inch 720p LCD HDTV, Black
Samsung LN32B460 32-Inch 720p LCD HDTV
Samsung LN32C450 32-Inch 720p 60 Hz LCD HDTV (Black)
VIZIO VA19LHDTV10T 19-Inch ECO 720p LCD HDTV
Samsung LN46B650 46-Inch 1080p 120 Hz LCD HDTV with Red Touch of Color
Toshiba 40RV525R 40-Inch 1080p LCD HDTV
VIZIO VA220E 22-Inch ECO 720p LCD HDTV
VIZIO VA370M 37-Inch Full HD 1080p LCD HDTV
Samsung LN26B360 26-Inch 720p LCD HDTV
Samsung SyncMaster 2333HD HDTV Widescreen LCD Monitor (Glossy Black)