Oral or verbal contract
In French law, the contract is defined by the civil code in article 1101. The code defines the contract as "an agreement of will". The agreement of will is the product of an encounter between an offer and an acceptance. This offer and acceptance may be oral or verbal. Concretely, a contract can be concluded by word, provided that it is concluded clearly.
The distinction between the contract and written evidence
Contracts are agreements of will. Contracts are not the most often resulting writing. The deal is called the business in law, the resulting writing is the instrumental. Some contracts are only valid if they are in writing, but this does not apply to most cases. So a contract is not a written document but the writing is the trace of the contract concluded.
proof of contract
It is up to the plaintiff to prove the existence of a contract. They consist of private or authentic writings which can all give rise to a dispute, however the written evidence is very strong, it is evidence literal.
But a contract can also be proved by so-called proofs testimonials. They are statements made on facts of which their authors have had personal knowledge; as well as the admission which consists in recognizing as true a fact likely to produce legal consequences against it.