what is exotic and non-exotic leather?

This might be a silly question.
what is exotic leather? and non-exotic leather?
I have no where else to learn better than here, thank you so much!!!
Exotic: crocodile, alligator, lizard, ostrich
Non-exotic: Togo, Clemance, Fjord, Epsom...etc..all other leathers except exotics that is mentioned above.