This chapter examines the rules of offer and acceptance in the formation of contract in Taiwan law. An offer is binding unless: the offer states otherwise, the revocation reaches the offeree before or at the same time as the offer, or if the offeree does not respond within a reasonable time. An acceptance only becomes effective when it reaches the offeror. The postal rule does not apply, but if the postal acceptance is delayed for reasons not attributable to the offeree, the offeror who knows of the delay must inform the offeree of it, otherwise the offeror will be bound at the time that the acceptance would normally have arrived. In a ‘battle of forms’ situation there is no binding contract if the different terms are core to the contract. Silence may amount to acceptance if communication of acceptance is waived by the offeror or by custom, or acceptance by conduct is inferred. There is no general requirement of form for a valid contract, but exceptionally, formalities are necessary.