In the French Civil Code, a donation is a solemn act. Note that there is a difference between a "présent d'usage" and a "don manuel".
A "présent d'usage" or "faux don manuel" is a gift made on the occasion of a specific event (birthday, anniversary, etc.). It must be proportional to the donor's wealth, and does not need to be declared. On the other hand, if you make a manual gift, you will be accountable for it to your heirs, so you need to declare it in order to start the statute of limitations for tax purposes.
A manual donation without a notary can be dangerous: see the video for explanations and examples.