A marathon is a very long race. It's usually 26 miles long, which is almost 42 kilometers. That's much longer than a regular race, and it takes a lot of strength and determination to finish. To get ready for it, people typically practice running for several months beforehand. On the day of the race, crowds of people gather to cheer on the runners as they make their way towards the finish line. Whoever finishes the race first is crowned the winner, and they are often rewarded with medals and other prizes.