Why does reducing trade barriers promote increased international trade?

Reducing trade barriers promotes increased international trade because it allows for more competition. This, in turn, can provide lower prices for consumers as well as an increase in productivity. Also, it may attract new partners and investors, which would also benefit a nation's economy. In the past, some nations have passed measures on international trade in efforts to protect themselves economically from foreign competition. Occasionally, this has resulted in a trade war among parties with devastating results financially. Today, the process of signing trade agreements has been a challenging process as each side is careful to not be taken advantage of by the other party.