Marilyn, I think you mean Coleus isn't a perennial in your area? It can't stay alive where I am outside over winter either, but it's still a perennial. Being taken to where it can't survive doesn't change a plants' basic status as a perennial. That's not a designation given by location, but, to avoid confusion and wrong expectations, plants sold outside of their realm of hardiness are labeled annuals.
Discovering which are really perennials is the first step to keeping the perennial ones alive inside over winter, for those who might want to do that. Many of the basic 'Rainbow' and 'Wizard' Coleus can be grown from seeds, but when one finds a cultivar that can only be vegetatively propagated, it can be worth saving if one would be bummed if unable to find it for sale again the next year.