World Trade Organisation
The World Trade Organization (WTO) is a international group of nations that meet to deal with several areas of concern, the first being the reaching of consensus on common trade policies. Such negotiation takes place in a general context that reducing international barriers to trade is desirable; an ideal, not necessarily realizable, is that all countriee extend most-favoured-nation status to one another.
It also provides a venue for resolving some trade disputes, under the realities of international economics and of the political conflicts of the world; it is not always successful.
Rules vs. organization
The WTO actually is younger than its principal set of rules, the General Agreement on Trade and Tariffs, first enacted in 1948, and updated by periodic multinational meetings called rounds. It was not until 1995 that the WTO itself was created.
Again, the WTO is the inheritor of agreements, beginning with the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) negotiated during the 1986-94 Uruguay Round, and organizations, specifically those of the World International Property Organization.
Its principal authority is in its member nations and government committees, but it also has a professional secretariat.