The Port of Singapore refers to the collective facilities and terminals that conduct maritime trade handling functions in harbours and which handle Singapore's shipping. Currently the world's second-busiest port in terms of total shipping tonnage, it also trans-ships a fifth of the world's shipping containers, half of the world's annual supply of crude oil, and is the world's busiest transshipment port. It was also the busiest port in terms of total cargo tonnage handled until 2005, when it was surpassed by the Port of Shanghai. Thousands of ships drop anchor in the harbour, connecting the port to over 600 other ports in 123 countries and spread over six continents.