4K, also known as Ultra HD or UHD, refers to a display resolution of 3840 x 2160 pixels, which is four times the resolution of 1080p, or Full HD. 4K displays have become increasingly popular in recent years, as they offer sharper, more detailed images and a more immersive viewing experience. 4K is commonly used in TVs, monitors, and other video displays, and is supported by many video streaming and content creation platforms. In addition to the increased resolution, 4K video also often includes a wider color gamut and higher frame rates, which can improve the overall quality and realism of the video.