High-definition television (HDTV) is a television system providing an image resolution that is of substantially higher resolution than that of standard-definition television. This can be either analog or digital. HDTV is the current standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television, Blu-rays, and streaming video.
HDTV may be transmitted in various formats:

720p (HD ready): 1280×720p: 923,600 pixels (~0.92 MP) per frame
1080i (full HD) : 1920×1080i: 1,036,800 pixels (~1.04 MP) per field or 2,073,600 pixels (~2.07 MP) per frame
1080p (full HD): 1920×1080p: 2,073,600 pixels (~2.07 megapixels) per frame
Some countries also use a non-standard CEA resolution, such as 1440×1080i: 777,600 pixels (~0.78 MP) per field or 1,555,200 pixels (~1.56 MP) per frameThe letter "p" here stands for progressive scan, while "i" indicates interlaced.
When transmitted at two megapixels per frame, HDTV provides about five times as many pixels as SD (standard-definition television). The increased resolution provides for a clearer, more detailed picture. In addition, progressive scan and higher frame rates result in a picture with less flicker and better rendering of fast motion. HDTV as is known today first started official broadcasting in 1989 in Japan, under the MUSE/Hi-Vision analog system. HDTV was widely adopted worldwide in the late 2000s.