What are treaties?
Treaties are written international agreements signed between public international law persons, such as states and international organisations, that are governed by public international law. Treaties may have different names such as international agreements, conventions, and protocols, but there is no difference in regard to legal effect between these names.
What is the difference between ratification and accession?
Ratification is the act by which a state declares its acceptable to be bound by the provisions of treaty after signing it. In regard to bilateral treaties, there is always an act of ratification after signing the agreement. If the state signs a multilateral treaty, the state will also have to follow the signing by an act of ratification.
Accession only relates to multilateral agreements, and it is the act by which a state declares its acceptable to be bound by the provisions of the treaty that was previously negotiated and signed by other states not including the state wishing to accede to it. Accession has the same effect as ratification, but it occurs after after a treaty becomes no longer open for signature.
When does a treaty enter into force?
Treaties enter into force according to the provisions specified in each treaty. For example, bilateral treaties usually enter into force after the exchange of the instruments of ratification, while multilateral treaties may enter into force after depositing the instruments of ratification or access by a specific number of states.