Welcome, birdfeed (I like the handle).

I am just learning about the complexity of isomers due to a post by wwh (familiarly know as Dr. Bill). I had known only what I think of as D-isomers and L-isomers for right and left handed versions of complex molecules that can be oriented in two different ways. There are other isomer pairs, notably endo and exo isomers, but them I have no idea what differentiates them. It gets kind of technical on the molecular level. As far as I know the choice of handedness in the designation of these molecules is purely arbitrary.