Chirality, while not a rarity in the world of molecules, is nevertheless a special property. If a molecule is chiral (from the Greek word chiros = hand), it exists in two mirrored versions that are very similar but not identical—like two hands that can be folded together, but cannot be placed congruently on top of each other. This is why we speak of right-handed and left-handed molecules, or enantiomers, which means "opposite shape" in Greek.
