ratification

Ratification is the international act by which a state indicates its consent to be bound to a treaty, where the parties intended their consent to be shown that way. That is the definition used by the United Nations Treaty Collection, which keeps the official register for treaties deposited with the Secretary-General.

The distinction from signature is the point. Where a signature is subject to ratification, acceptance or approval, the signature does not establish consent to be bound: it authenticates the text and expresses the willingness of the signing state to carry on with the treaty-making process. A country can therefore sit on a list of signatories for years while carrying none of the treaty's obligations. Accession is the parallel route for a state that joins a treaty already negotiated and signed by others, and it has the same legal effect as ratification.

Ratifications are also what start a treaty running. A treaty normally sets a threshold in its own text, and it enters into force once enough instruments have been deposited. That is why a depositary register reports two separate counts, signatories on one side and parties on the other, and why only the second one tells you who is bound.