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High-definition television (HDTV) is a television broadcasting system which uses a higher resolution than a normal television. With HDTV, people can see sharper pictures than with old television, giving a more vivid and clear screen.

Most HDTV systems use digital signals with a 16:9 aspect ratio (width to height). This is different to SDTV (standard-definition television) which uses analog signals and a 4:3 aspect ratio.

HDTV picture resolution is at least twice that of SDTV, so it can present a more vivid screen than analog television or DVD. HDTV can control resolution efficiently.

Many videos on the website YouTube, a free video sharing website that lets people upload and view videos, are in HD.

There are different standards. Common ones are:

• 2560×1440, progressive scan, requiring about 3,68 Megapixels per frame. This is known as 1440p or WQHD. It is a new standard, which is slowly replacing many 1080p-computer-monitors in the everyday use.
• 1920×1080, progressive scan, requiring about 2,07 MPixels per frame. This is known as 1080p or FullHD. It has been used very frequently for different types of screens in the past few years.
• 1920×1080, interlaced, 1.04 MPixel per field. This is known as 1080i.
• 1280×720, progressive, 0.92 MPixel per frame. This is known as 720p.
• 1280×720, interlaced, 0.46 MPixel per field. This is known as 720i.

As a comparison, PAL plus is at 1024x576 pixels, and NTSC at 853x480 pixels.

• US Government HDTV and DTV official site Archived 2011-07-25 at the Wayback Machine
• Canadian Digital Television official website Archived 2006-02-28 at the Wayback Machine
• ATSC