4K video playback refers to the ability to play video content with a resolution of 3840 x 2160 pixels, which is four times the resolution of 1080p (1920 x 1080 pixels). This higher resolution provides sharper images and more detail, making it ideal for large screens and immersive viewing experiences. To enjoy 4K video playback, you need a compatible device, such as a 4K TV or monitor, and a source of 4K content, like streaming services or Ultra HD Blu-ray discs. Additionally, a strong internet connection is often required for smooth streaming of high-resolution videos.