Where is the opengl sdk?

Hi,i just started out with graphics programming recently so the first thing i did was d/l the directx sdk. I thought i would try direct3d for a week then opengl and decide which one i liked best. On the opengl site there is no link to the sdk, i mean is there one?
If not, what is the latest version of whatever it is i need and how do i get it?
Sorry if this has been asked a million times

i think that gl sdk does not exist!
but you could use NV SDK (which contains their gl sdk, and their d3d sdk) or ATI’s SDK
there is a lot of samples!
here: http://developer.nvidia.com/object/LO_20030224_3527.html