What is Resolution of Monitor? Full HD vs 2K vs 4K

As you may know, many displays or monitors nowadays boast about having 4K UHD (Ultra HD); however, what exactly is 4K UHD, and how is it different from the Full HD we were used to seeing in the past?

2K vs. 4K: What's the Difference Between These Display Resolutions? - History-Computer

What is the difference between hd, full hd, ultra hd, 2K, 4k, 8k, 10K resolutions?

What is Resolution of Monitor? Full HD vs 2K vs 4K

2560×1440 vs 3840x2160 [Which Should I Choose?] - Display Ninja

720p vs 1080p vs 1440p vs 4K vs 8K - Which Should I Choose? [Simple]

1920x1080 vs 2560x1440 - Which Should I Choose? [Simple]

What is the difference between hd, full hd, ultra hd, 2K, 4k, 8k, 10K resolutions?

Why 2K is BETTER Than 4K for PC Gaming 1440p Resolution Explained - Video Summarizer - Glarity

2k vs 4k Resolution: Which Should You Choose?