A cruise missile is basically a small, pilotless airplane. Cruise missiles have an 8.5-foot (2.61-meter) wingspan, are powered by turbofan engines and can fly 500 to 1,000 miles (805 to 1,610 km) depending on the configuration.
A cruise missile's job in life is to deliver a 1,000-pound (450-kg) high-explosive bomb to a precise location -- the target. The missile is destroyed when the bomb explodes. Since cruise missiles cost between $500,000 and $1,000,000 each, it's a fairly expensive way to deliver a 1,000-pound package.
Cruise missiles come in a number of variations (see the links at the end of the article for more information) and can be launched from submarines, destroyers or aircraft.
When you hear about hundreds of cruise missiles being fired at targets, they are almost always Tomahawk cruise missiles launched from destroyers.