The supreme God, Eru Ilúvatar, created the humans after the Elves, and as such they are sometimes referred to as the Afterborn. They awoke three Ages after the Elves did, after the sun rose for the first time at the start of the First Age.
While Elves are immortal, Men bear the Gift of Men, the gift of mortality. Unlike Elves, men will age and eventually die. They can also be affected by illness and disease. When a Man dies, their spirit leaves Arda, whereas an Elven spirit is bound to Arda and remains in the Halls of Mandos.