I'm going to say what the psych book said. ID- Inner Desires, what we desire to do ect ect. (action) Ego-The I with out caring what others might think if we enforce our ID (kid) Superego- the force that keeps both the Ego and the ID in line. (parent)
..so the ego is a construct of the mind which changes in form as a person develops...or it stagnates at some level and no further devlopment takes place.