<Li> An exception exists in the case of unilateral contracts, in which the offeror makes an offer to the world which can be accepted by some act . A classic instance of this is the case of Carlill v. Carbolic Smoke Ball Co. (1893) 2 Q.B. 484 in which an offer was made to pay £ 100 to anyone who having bought the offeror's product and used it in accordance with the instructions nonetheless contracted influenza . The plaintiff who was Mrs Carlill bought the smoke ball and used it according to the instructions but she contracted influenza. She sued the Carbolic Smoke Ball Co. for £ 100 . The court held that the inconvenience she went through by performing the act amounted to acceptance and therefore ordered £ 100 to be given to Mrs. Carlill . Her actions accepted the offer - there was no need to communicate acceptance . Typical cases of unilateral offers are advertisements of rewards (e.g., for the return of a lost dog). </Li> <Li> An offer can only be accepted by the offeree, that is, the person to whom the offer is made . </Li> <Li> An offeree is not usually bound if another person accepts the offer on their behalf without his authorisation, the exceptions to which are found in the law of agency, where an agent may have apparent or ostensible authority, or the usual authority of an agent in the particular market, even if the principal did not realise what the extent of this authority was, and someone on whose behalf an offer has been purportedly accepted may also ratify the contract within a reasonable time, binding both parties: see agent (law). </Li> <Li> It may be implied from the construction of the contract that the offeror has dispensed with the requirement of communication of acceptance (called waiver of communication - which is generally implied in unilateral contracts). </Li>

When is an offer to purchase considered accepted