Transportation is important because it facilitates trade, exchange and travel. Without effective transportation, regions are largely isolated from each other. Effective, affordable transportation also plays a role in letting people move to new areas.
The ship is the earliest form of transportation to have a significant effect on trade, and ships still play a crucial role in transporting large quantities of goods. Ships can operate on nothing more than the wind, mitigating the needs for engines in the earliest designs.
The train revolutionized modern business, and it helped create the modern world. Before the invention of the steam engine, goods had to be transported in small amounts. The cost of purchasing foreign goods was simply too high for many to afford, and goods that could not be shipped by boat were prohibitively expensive for most of the middle class.
The airplane has made long-distance transportation a reality for many, and people are able to travel across nations and around the world for relatively low costs. While travel by rail is still popular, airplanes are credited with making trans-Atlantic and trans-Pacific travel a reality. While airplane tickets can be expensive, they pale in comparison to the cost of crossing an ocean by boat, and planes take only hours instead of weeks or even months to get to their destination.