A portrait represents graphically the physical features and the personality of a person.
A good expression is not enough. Only one out of all possibilities is the one that will really capture the personality. That is the essence of a portrait.
Portraits can be made for different occasions: weddings, communions, individual ones, etc. Thus, we can see commercial portraits done in the studio, outdoors and indoors.
I have also included a sort of family tree that I gave to my parents as a present for their wedding anniversary in my portfolio.