Since 1955, the volume of the world trade has grown much faster than the world economy as a whole, and for many countries it has been the engine of growth.
The gains of trade have been unevenly distributed, as first Europe, and then Asia joined the world trading system.
Other poor regions, such as Africa, dependent on commodities, have been left behind.
Trade talks helped boost trade in manufactured goods between rich countries as tariffs were cut.
Countries which aimed at export-led growth, such as Japan, Korea, and China, have benefited.
But liberalising trade in services - such as accounting - or agriculture has proved harder.
Now talks aimed at opening up markets in agriculture to benefit poor developing countries have stalled.