What is WTO? When and why it is established?

World Trade Organisation (WTO) is one such organisation whose aim is to liberalise international trade. Started at the initiative of the developed countries, WTO establishes rules regarding international trade, and sees that these rules are obeyed. At present 164 countries of the world are currently members of the WTO. Though WTO is supposed to allow free trade for all, in practice, it is seen that the developed countries have unfairly retained trade barriers. On the other hand, WTO rules have forced the developing countries to remove trade barriers. An example of this is the current debate on trade in agricultural products.