Restatement 2d § 24
An offer is the manifestation of willingness to enter into a bargain;
so made as to justify another person in understanding that assent to that bargain is invited;
will conclude it
Restatement 2d § 30
1. an offer may invite or require acceptance to be made by an affirmative answer in words or by performing or deciding not to performa specified act
2. Unless otherwise indicated by the language an offer invites acceptance in any manner and by any medium reasonable in the circumstances.
Restatement 2d § 35
An offer gives to the offeree a continuing power to complete the manifestation of mutual assent by acceptance of the offer.
Restatement 2s § 45
Where an offer invites an offeree to accept by rendering a performance, an option contract is created when the offeree tenders or begins the invited performance.
Restatement 2d § 54
Where an offer invites an offeree to accept by rendering a performance, no notification is necessary to make such an acceptance effective unless the offer requests such a notification.
Restatement 2d § 62
Where an offer invites an offeree to choose between acceptance by promise and acceptance by performance, the beginning of the invited performance or tender of is acceptance by performance
Restatement 2d § 69
1. An offeree's silence and inaction is not recognized as acceptance unless:
a. an offeree takes benefit of offered services with reasonable opportunity to reject them and reason to know that they were offered with the expecation of compensation.
b. the offeror has stated or given the offeree reason to understand that assent may be manifest by silence
c. because of previous dealings, it is reasonable that the offeree should notify the offeror if he does not intent to accept.