4K or Ultra HD

Let's start at the top of the current TV market: 4K. This is a good place to begin, as it lets us talk about the basis for the vast majority of the confusion when it comes to resolution.

The short version is this: When it comes to TVs, 4K and Ultra HD (or UHD) are referring to the same resolution. Those TVs, along with Ultra HD Blu-ray, and nearly all UHD streaming content from Netflix, Amazon and others, is 3,840x2,160 resolution.

Here's the long version:

Technically, "4K" means a horizontal resolution of 4,096 pixels. This is the resolution set forth by the Digital Cinema Initiatives. Because movies vary in aspect ratio, which refers to the exact shape of the rectangle of screen, no vertical resolution is specified.

Ultra HD TVs aren't technically "4K" since their resolution is 3,840x2,160. However, it doesn't matter. 4K is way easier to say than 2,160p or Ultra HD, and when anyone runs a survey asking about it, the vast majority of you (and us, FWIW), greatly prefer "4K."