Computer screen formats have always had odd names, such as VGA and SVGA, to describe the differing pixel dimensions. As more powerful graphic cards became available, thus allowing computer monitors to increase in size, then new format names have appeared. Most dimensions have been in the same width to height ratio of 4:3. There are exceptions, such as SXGA, which have the squarer ratio of 5:4 that the traditional television monitors were supplied in. Older monitors were usually either 14 or 15 inches in size (measured in diagonal screen width), and so used the VGA or SVGA settings for the best fit. But with larger 17 and 19 inch monitors the XGA setting became more common. As the screen sizes increased, then larger pixel dimensions were needed to allow the screen resolution to be kept to a high enough quality.
Along with the growth of Liquid Crystal monitors (LCDs), or flat screens, have come newer wide screen formats. The wide format did exist before with Cathode Ray Tube monitors (CRTs), but as it meant they were very heavy and took up a huge amount of desk space they did not become popular. Now that LCDs are affordable, the wide screen formats will become more common and eventually replace the standard formats, just as CRTs are being replaced. The wide screen resolutions are usually in the 16:9 or 16:10 ratios. They also have a new set of format names, which are basically the same as the standard formats but with W added, such as WVGA and WXGA.