A continental margin is made up of the continental shelf, the continental slope and the continental rise. According to Dictionary.com, a continental margin is the offshore zone that separates a continent's dry land portion from the deep floor of the ocean.
Wikipedia states that continental margins make up approximately 28 percent of oceanic area. The continental shelf is the part of the continental crust that is underwater. The continental slope is the deep slope that separates the continental shelf from the deep ocean basin. The continental rise is the outer area of the margin where the continental crust typically transitions to the oceanic crust.