International agreements are an indispensable tool of diplomacy and much of daily life activities are governed by international agreements. All types of daily activities involving more than one state such as telecommunications, air transport, trade etc that are taken for granted will not be possible without international agreements being in place to regulate these activities.
International agreements are governed by the law of treaties, which is one of the cornerstones of international law. The Vienna Convention on the Law of Treaties that was signed in 1969 and entered into force in 1980 is a multilateral treaty and a mixture of the codification of existing international treaty law and the progressive development thereof. It is regarded as declaratory of customary international law and binds all states regardless of whether they are a party to it or not.
South Africa is not a party to the Vienna Convention on the Law of Treaties, but is bound to the provisions of the convention.