Free trade is a controversial but important doctrine in economics, typically promoted as enabling countries to specialize in the production of items they can produce with the least sacrifice. Trade theory developed in an era when some countries made manufactured goods, while others provided raw materials. The term has now lasted into an era when most manufactured trade is actually between similar countries in similar products. It can also now refer to low levels of government regulation of so-called invisible trade, in services and cross-border financial flows — Evan Davis