A half marathon is a highway working occasion of 13.1 miles (21.1 km), usually run as a single loop course. The half marathon is the fourth hottest long-distance working occasion after the marathon, 10K run, and 5K run.
The half marathon distance has been run competitively because the early twentieth century, with the primary official world championship race being held in 1992. The half marathon is now an Olympic occasion, and can also be included within the World Athletics Championships and different main worldwide athletics competitions.