Hello, I recently started looking into OpenGL and I was wondering what version of OpenGL I should target? I'm guessing that you should provide compatibility with older versions and such, but how "far back" should I go? I've been looking up these extension loading libraries but I was wondering if it's possible to accomplish reasonable compatibility without these. The specifications for each version of OpenGL is quite a read and because of my limited knowledge of working with OpenGL I could not possible grasp all of the content and make a decision on my earlier question.

If I were to write my own, do I need to check for each version of OpenGL available and make adjustments during runtime to what functions my application uses? Are there a lot of functions that I will not (normally) use which are added in the later versions of OpenGL, can I disregard these?

Note: I figured I would bite the bullet and learn this kind of tedious stuff earlier than have problems later, so please, tell me all the work required to accomplish this.

Help is very much appreciated and if my terminology is off, please excuse me.