It is most common for those racing in short events (e.g., sprinters and even some middle-distance runners) to hit the ground on the balls of their feet, almost as if they are running on their toes. On the other hand, many longer-distance runners, which certainly includes those who are running a marathon, tend to strike the ground with a heel-first landing or, in some cases, a midfoot landing.
A big advantage of a mid- or rear-foot landing is that it reduces the stress placed on the calf muscles and shifts the landing stress more to the larger thigh muscles. It is not uncommon for beginner runners to develop calf pain, and forefoot landings add to that possibility. If using a heel-first landing, try to imagine you are rolling over your feet as your body moves forward after each landing, as previously stated.