Article 43 — Formation of Contracts

1. 1.

   A contract is formed by the exchange of concordant declarations of will: an offer and an acceptance.

2. 2.

   An offer is a proposal sufficiently definite as to its essential terms, made with the intention of being bound upon acceptance. An offer may be revoked at any time before acceptance, unless the offeror has undertaken to hold it open for a stated period.

3. 3.

   Acceptance is the unqualified assent to the terms of the offer. An acceptance that modifies the terms of the offer is a counter-offer.

4. 4.

   A contract is concluded at the moment when acceptance reaches the offeror, or at such earlier moment as the parties have agreed.

5. 5.

   Silence does not constitute acceptance unless the parties have so agreed by prior course of dealing or established practice.