The oldest high-definition technology is 720p. 720p televisions support resolutions up to 1,280 by 720 pixels. Although it is of lower quality, 720p resolution still looks like high definition, especially if the television you buy is on the smaller side, measuring 37 inches or lower. As such, this technology is ideal if you intend to use your new television primarily for watching television programs and DVDs.
If you are planning on using your new television for watching Blu-Ray discs or for console gaming, however, you probably want to look at a 1080p television. These televisions support resolutions up to 1,920 by 1,080 pixels. Television programs also look somewhat better on a 1080p television as most stations transmit their signals in 1080i.
The newest forthcoming technologies are Ultra HD and 4K. Ultra HD televisions are 2160p, and they usually measure 80 inches or more. Ultra HD is also known as 4K because the number of pixels in a horizontal row is roughly 4,000. The actual resolution is 3,840 by 2,160 pixels. Ultra HD is appropriate if you have a particularly large room in which viewers sit several meters from the television.
Determining the resolution you need in a new television is largely a process of defining your entertainment needs. If you want a larger television, you need a higher definition to avoid pixelation. In general, you need higher resolution to support newer technologies. For example, 720p is fine for DVDs, but you need a 1080p or better television for watching Blu-Rays to create the ideal viewing experience.