A hurricane is a large storm characterised by very strong winds. If a tropical cyclone has winds over 74mph(119km/h) and it forms in the Atlantic Ocean, it is known as a hurricane. There are 5 categories of hurricane numbered 1 to 5. The most severe category 5 hurricanes can have winds up to 200mph(320km/h). The hurricane develops around an area of low pressure(the eye) and the winds rotate in an anti clockwise direction around this point. This is what they look like from space.
A hurricane is specific to the area around the USA. A tropical storm formed in the Indian Ocean is called a cyclone, and one formed in the Western Pacific Ocean is called a typhoon.
For more in depth information on hurricanes, please see the following link:
An excellent page from Weather Wiz Kids
For a video on hurricanes, please see below.