A locomotive is a powerful engine that pulls trains along railroad tracks. Unlike regular train cars that just carry passengers or freight, a locomotive contains the engine that makes the whole train move. The most iconic locomotives burn coal or diesel fuel to create the power needed to pull dozens of heavy cars behind them, sometimes weighing thousands of tons.

Before locomotives, trains were pulled by horses or moved along cables. The invention of the steam locomotive in the early 1800s revolutionized transportation, making it possible to move people and goods across continents faster than ever before. Cities that were weeks apart by horse and wagon suddenly became connected by a day's train ride.

Modern locomotives use diesel engines or electricity, but they serve the same purpose: providing the muscle that moves trains. When you see a train passing by, the locomotive is usually at the front, sometimes painted in bold colors or marked with the railroad company’s logo. Some long freight trains even need multiple locomotives working together to pull their load.