| A | B |
| contract | any agreement enforceable by law |
| void contract | a contract with no legal effect |
| voidable contract | a contract in which one of the parties can cancel |
| unenforceable contract | a contract that can't be upheld by the courts because of a rule of law |
| express contract | stated in words either oral or written |
| implied contract | contract comes about because of the actions of the parties |
| bilateral contract | contract with two promises |
| unilateral contract | a promise by one person to do something when the other party performs some act |
| invitation to negotiate | an invitation to deal, trade or make an offer |
| mirror image rule | the acceptance of an offer must not change the terms of the original offer in any way |
| counteroffer | any change in the terms of the offer that means the offeree has not really accepted the offer |
| revocation | taking back of an offer by the offeror |
| rejection | a refusal of an offer by the offeree |