How to correct a sagging entry door?

Thanks everyone for your help. But I need to clarify what I mean by sagging. Although I haven't checked the door for being square I don't think it's really "askew". However, I will check it out. What I'm dealing with is more of a straight down sag on the hinges. The soft aluminum on the door jamb is being worn away by the weight of the door. I will need to take pictures to help illustrate the condition. I've had one suggestion to lift the door to remove the slack and add two or three normal hinges. This would place the hinge pin on the outside of the door. But it was thought that the added hinges would carry the weight and are replaceable whereas the jamb side of the door hinge is part of the door jamb and therefore not replaceable. Does any of this help or make since?

Ken