A marathon is a long-distance running race with an official standard distance of 42.195 kilometers, which is approximately 26.2 miles. The length of a marathon was standardized during the 1908 London Olympics when the race was held over this distance to accommodate the royal family's desire to start the race at Windsor Castle and finish it in front of the royal box at the Olympic Stadium.

The marathon's name and distance have historical significance dating back to the Battle of Marathon in 490 B.C., during which a Greek messenger named Pheidippides is said to have run from the town of Marathon to Athens to deliver news of a military victory. The distance he reportedly covered was roughly 42 kilometers.

Today, the marathon is one of the most iconic and prestigious long-distance running events globally, attracting both professional and amateur runners from around the world. It is the ultimate test of endurance and requires months of rigorous training for participants to prepare their bodies for the physical and mental challenges of covering the 26.2-mile distance.

Marathons are held in various cities and regions worldwide, and they often serve as major sporting events and fundraisers for charitable causes. The most famous marathon is the Boston Marathon, one of the oldest and most prestigious races, which has been held annually since 1897 on Patriot's Day in April. Other renowned marathons include the New York City Marathon, the London Marathon, and the Berlin Marathon, among many others.

Completing a marathon is a significant achievement for runners of all levels, and participants often set personal goals for their finishing times. The sense of accomplishment and the physical and mental challenges overcome during the race contribute to the enduring appeal of the marathon as a symbol of human determination and athletic excellence.