What does the WTO trade deal actually mean?

A "historic" deal reached by global trade ministers could be worth $1bn (£600m) a year to British business, Prime Minister David Cameron has said.

The World Trade Organization has agreed on trading terms for the first time since its foundation in 1995, with procedures to be simplified and some export tariffs for poorer nations cut.

The BBC's chief business correspondent Linda Yueh explains what the finer details of the World Trade Organization trade deal actually mean.