I've never gotten around this thing because I don't really understand this tech stuff. Googling gives me results and explanations in such a way as if they assume I already know what it is.

Can soembody explain in simple language how exactly is this different when playing games? Like I got a choice of taking DirectX or OpenGL. What's the difference? Also somebody told me that OpenGL doesn't work on hardware but rather on software - or something like that, can't remember properly.