A tanker is a large ship specially designed to carry liquid cargo in huge quantities. Unlike regular cargo ships that transport boxes and containers, tankers have enormous tanks built into their hulls to hold liquids like oil, gasoline, or chemicals. Some tankers are among the biggest ships ever built: the largest oil tankers can be longer than the Empire State Building is tall and carry millions of gallons of fuel.

Oil tankers supply the gasoline that powers cars and airplanes around the world. When you see gas being pumped at a service station, it probably arrived in your country aboard a tanker that crossed an ocean. Other tankers carry natural gas, orange juice, or even liquid chocolate.

The word can also refer to aircraft that carry fuel for other planes. Military tanker planes fly alongside fighter jets and refuel them in midair, letting them fly much longer distances without landing.

You might also hear tanker truck for the large trucks that deliver gasoline to gas stations or heating oil to homes. Whether on land, sea, or in the air, tankers share one purpose: moving large amounts of liquid from where it's produced to where it's needed.