Many businesses get tripped up in differentiating between unilateral and bilateral contracts.

This confusion could be quite costly.  A bilateral contract is one in which each party promises some performance.  In a unilateral contract, one party makes an offer in the form of a promise to perform an act or forbear upon the fulfillment of certain conditions by the other party.  The party making the offer in the form of a promise is bound if the other party acts in accordance with the offer.  That other party is not bound.  It may choose to not act at all.  The offering business believes it has been wronged because the other party failed to perform, when in fact the other party never had the legal obligation to perform.  This is especially confusing when all communication is verbal.