HD stands for High Definition. It refers to a digital or analog video signal with more than 720 lines of horizontal resolution, offering a much clearer and sharper image than standard definition (SD) television. The term has been used since at least 1933, and in recent times, it represents the generation following standard-definition television.
HD technology has become the standard for television broadcasting, DVD and Blu-ray discs, and video cameras. You might also see terms like "Full HD" (1080p) or "4K UHD" (3840 x 2160 pixels), which are specific resolutions within the HD category.
