API :In the early days when 3d cards came into existance
	they all supported different standard and features because
	of this the application program had to be specially written 
	with a particular in mind it was not sure wether the same 
	program would work on some other card this made life 
	difficult for the programmers. So API's(application 
	programming interface were developed .These API's form a 
	layer between the application program and the hardware and 
	resolve the incompatablity to quite an extent.There are 
	many different API's out of which ther three major API's 
	are as follows.............	
  3Dfx Glide:Glide was one of the first API for the windows 
 	platform and was written specifically for the 3Dfx Voodoo
	range of cards which were also the first 3d cards avaliable 
	for the windows platform.It is considered to be a very good 
	API with nice special effects and features and is widely 
	supported by most of the older and quite a few newer games.
	THe problem with this api is that it can work only on the 
	3Dfx Voodoo range of cards.
  Direct X:This API developed by Microsoft is one of the most 
	popular not because it is the best but more so because of
	Microsofts dominance in the PC market.Though it has improved
	a lot and is improving many feel it still cannot match the 
	visual quality and beauty of other API like openGL or for 
	that matter even that of Glide.All the grapic card avaliable 
	in the market have support for this API.
  OpenGL:It is the oldest and considered to be the best API.
	It was originally developed for the UNIX platform and was 
	developed by Silicon Graphic a pioneer in 3d computing for 
	those who do not know movies like Jurassic Park and Titanic 
	were all developed on silicon graphic machines.In 1996-97
	Microsoft and Silicon graphics brought support for this API
	to the windows platform.Support for this API is avaliable 
	in to forms ICD(Installable Client Drivers) and MCD(Mini
	Client Drivers) IC Drivers are specifically tuned for a
	particular card which requires more effort and time but 
	gives suprior performance.These are made avaliable by the 
	card manufacturers along with the card drivers.MC Drivers
	can be quickly and easily made for a card but they are not
	optimised or accelerated and so have a inferior performance
	but are sure to work on any system.