H.D. (High-Definition) refers to a resolution standard that provides clearer and more detailed images compared to standard definition. It typically includes resolutions such as 720p, 1080p, and 4K, which indicate the number of horizontal lines of pixels. Higher resolutions result in sharper visuals, making it ideal for viewing on large screens, such as televisions and monitors. High-Definition is commonly used in various media formats, including television broadcasts, streaming services, and Blu-ray discs. The transition to H.D. has enhanced the viewing experience for audiences, allowing for more immersive and lifelike images in movies, sports, and video games.