Much shipping is done by actual ships. An individual nation's fleet and the people that crew it are referred to as its merchant navy or merchant marine. Merchant shipping is the lifeblood of the world economy, carrying 90% of international trade with 102,194 commercial ships worldwide. On rivers and canals, barges are often used to carry bulk cargo.
Sea transport has been the largest carrier of freight throughout recorded history. Although the importance of sea travel for passengers has decreased due to aviation, it is effective for short trips and pleasure cruises. Transport by water is cheaper than transport by air, despite fluctuating exchange rates and CAF charges to account for such.
Ship transport can be realized over any distance by boat, ship, sailboat or barge, over oceans and lakes, through canals or along rivers. Shipping may be for commerce, recreation or the military purpose. Virtually any material can be moved by water; however, water transport becomes impractical when material delivery is highly time-critical.