Conditions may be precedent, concurrent, or subsequent. A condition precedent is one which is to be performed before some right dependent thereon accrues, or some act dependent thereon is performed. Conditions concurrent are those which are mutually dependent, and are to be performed at the same time. A condition subsequent is one referring to a future event, upon happening of which the obligation becomes no longer binding upon the other party, if he chooses to avail himself of the condition.
SDCL 20-2-4