Competitive marathon running events are delineated primarily by distance, with the standard marathon being *42.195 kilometers* (26.2 miles). They often feature strict rules concerning pacing, hydration, and performance standards to ensure fair competition. Additionally, these events may have qualifying times, which athletes need to meet to enter major marathons, such as the Boston Marathon. The level of preparation and dedication required highlights the significance of discipline and endurance in the competitive marathon scene.