4K resolution, also known as Ultra High Definition (UHD), refers to a display resolution of 3840 x 2160 pixels. This is four times the resolution of 1080p, which was once considered the gold standard for high-definition video. The increased pixel density of 4K resolution provides a more detailed and immersive viewing experience, making it ideal for a wide range of applications, from movies and TV shows to video games and live sports.