2-D
Short for two-dimensional, 2-D is any virtual object with no appearance of depth. For example, if a graphic or image is 2-D, it can only be viewed properly from a straight on viewpoint. However, a 3-D graphic or image is viewable at any angle.
2-D computer graphics are used in applications that were developed around traditional printing and drawing technologies. Typography, cartography, technical drawing, and advertising are examples of applications and technologies that originally used 2-D computer graphics. In those applications, the two-dimensional image is not only a representation of a real-world object, but also an independent artifact with added semantic value. Two-dimensional models are often preferred because they give more direct control of the image than 3-D computer graphics (whose approach is more akin to photography than to typography).
With desktop publishing, engineering, and business, a 2-D computer graphic can be smaller than the corresponding digital image, often by a factor of 1/1000 or more. This representation is also more flexible since it can be rendered in different resolutions for different output devices. For these reasons, documents and illustrations are often stored or transmitted as 2-D graphic files.
2-D computer graphics started in the 1950s, based on vector graphics devices. These were largely supplanted by raster-based devices in the following decades. The PostScript language and the X Window System protocol were landmark developments in the field.