That’s why when you buy a TV you’ll see it advertised as supporting 4K, or on smaller screens, 1080p, and similar. Pixels are the building blocks for every display you’ve ever seen.

Comparison of pixel counts Here's a breakdown of the pixel counts for 1080p, 2K and 4K: 1080p: 1920 pixels wide by 1080 pixels tall. 2K (or 1440p): 2560 pixels wide by 1440 pixels tall.