Many modern PCs still use the over 20 year old 15 pin analogue VGA connector to connect the display to PC. The VGA connector carries the video signal in RGB format, which is a bit outdated in the world where the graphics card and display devices are all digital. Most Windows PC builders have been clinging to VGA to support legacy displays, especially in corporate environments where companies have often been hesitant or unable to update to modern screens and projectors.
The digital display interfaces have thought to replace the analogue VGA interface long time ago, but it has not happened yet. But maybe after few years it might happen. Apple was one of the first to abandon VGA in its products, adopting first DVI and later the DisplayPort and derivative Mini DisplayPort standards for its notebooks and desktops.
AMD, Intel, PC builders plan to drop VGA by 2015 article tells: AMD, Dell, Intel, Lenovo, Samsung and LG on Wednesday said they plan on focusing on putting digital DisplayPort and HDMI connections into their computer products. They hope to drop analog VGA and LVDS connections in AMD- and Intel-based products by 2015.
The article says that AMD CTO of the graphics division Eric Demers believed DisplayPort 1.2 is the future interface for PC monitors and HDMI 1.4a is the next step for TVs. DisplayPort is backwards compatible with VGA and DVI thanks to adapters.