It is common to see an author convey their rights to a third party, for instance to a publisher, who will thereafter manage the exploitation of the work in accordance with the clauses written down in a contract.
Therefore any exploitation contract for a work must bear explicit mention of its conditions of exploitation: from financial conditions to conveyed rights, to relevant geographical zones and to duration of the exploitation contract…
Each right conveyed must be explicitly mentioned, failing which it remains under the author’s responsibility.

The Creative Commons movement, inspired by Open Source, offers 6 types of contracts or "licences" which allow an author to make their work available to the public online, under certain conditions of use defined by him beforehand. The objective is to encourage, in a legal frame, the availability and circulation of works to promote exchanges and creativity, including in the context of academic research.
By the same token, a doctoral student may upload their thesis on HAL to increase its circulation.

Dicover creative commons with this video

Licence Creative Commons : CC-BY (2.5).