Has the the always been sticking. If so shaving off the sides, top or bottom could help.
If this is a problem that has developed over time, you should check to see if the hinges have become lose, or perhaps bend. Check the opening between the door and the jamb on the hinge side of the door, if the gap is bigger towards the top, fixing the hinge is the best solution. If the binding occurs on the botoom between the door and the threshold, check the gap between the door and the jamb across the top, if the gap is bigger towards the handle side, the door most likely is sagging. Use a carpenter's square to check if the doors side and top are at a 90 degree angle, or check to see if the joins are tight. You may need to buy a new door, or maybe you can carefully take the joins apart an re-glue them.
Also check the door frame is it square?
I live in an old house, and some doors that are binding during summer are not binding during winter and vice versa due to changes in the wood because of the humidity. Some floors seem to be sagging, hopefully that is not the problem at your house.