Case: carlill v carbolic smoke ball company conditional acceptance occurs when acceptation partly agrees to deal provided some changes are made. A request for info clarification is not a counter offer. mirror image rule. The intention to be legally bound is implied in commercial agreements. Dickinson v. dodds : offer can be revoked or lapse with time. Could be dependent on a condition precedent. Acceptance: can be: conditional, essentially a counter offer, expressed directly so that a bilateral contract is formed, or, implied by actions, creating a unilateral contract: carlill v. carbolic smoke ball co. What you pay for what you get. Need not be of equal value to what is being received, but must have value to the recipient if grossly unequal, courts might rectify. Gratuitous promises lack consideration, therefore are not enforceable except if written and under seal. Promissory estoppel is possible if charity entailed expenses in reliance. A seal is used where there is no consideration.