Trains can run on different sources of power, including:

• Steam: Steam was the first fuel source used to power trains, and most steam engines used today are primarily for tourism or historic purposes.

• Electricity: Many trains operate solely on electrical power, which they get from a third rail or electrical line. Electric trains have become more efficient and environmentally friendly over time, and some are even exploring the use of low- and zero-emission technology like battery-electric and hydrogen fuel cell locomotives.

• Diesel: Most modern trains run on diesel-electric combinations, where diesel is used to power the main alternator, which produces electricity for the traction motors that move the train.

• Biodiesel and renewable fuels: Railroads are now using renewable diesel and biodiesel blends to power their locomotives, which can make them even more environmentally responsible transportation solutions.

Trains are designed to a certain gauge, or distance between rails, and most operate on steel tracks with steel wheels, which makes them more efficient than other forms of transport.