A 2D video is a type of animation that exists in a two-dimensional space, focusing on height and width but lacking depth, which is the third dimension present in 3D animations. This makes 2D videos flat, with characters and backgrounds illustrated and animated within the same plane. 2D videos are commonly used in cartoons, advertisements, explainer videos, educational materials, and video games, offering a visually appealing but simpler form of storytelling and visual representation compared to their 3D counterparts.