The offer must be precise and complete, it may be tacit, implied or express and can not be withdrawn before the fixed date or a reasonable period of time.

Acceptance is adherence to the precise content of the offer, it may be tacit or Express.

Silence, in principle, is not worth accepting. However, silence may be accepted in several cases:

• If the terms of the obligation are in favor of the debtor only, the silence of the debtor party is worth acceptance.
• If the parties are accustomed to contracting together for the purpose of their activity, the silence of one of the parties may be accepted.
• If the parties have explicitly foreseen that silence would be valid

Defects in consent are a concept of the law of French contracts, which affect a variety of acts ranging from marriage, labor, or commercial contracts to consent to sexual

The defects of consent are used to carry out a procedural control of the contract, that is, the emphasis is placed on the manner in which the contract was formed and not on the substance of the contract itself Object, and by extension, the cause).

This control of the integrity of consent, which must be given freely and in an informed manner, is rendered essential by reason of the primacy accorded in French law to consensualism.

Consent being the essence of the contract, it is necessary to ensure its “quality”. A defect of consent results in the nullity of the contract, that is, its retroactive cancellation (the contract is assumed never to have existed).

These vices of consent are listed in sections 1130 error, fraud and violence ) And 1118 of the French Civil Code.