If you're remodelling your home, you might come across a situation in which a door that swings one way needs to swing the other way for everything to work correctly. This isn't as bad as it might sound. Door hinges are inset into the edge of the door, and can usually be put in any position you want them. Remember that you'll have to reverse the latch as well.
Remove the door by taking out the screws that hold the hinge plates against the jamb with your screw gun. Set the door on its front edge, with the hinged side facing up at you. The hinge plates that were attached to the jamb should be hanging off one side of the edge, connected by a pin to a second hinge plate inset into the door.
Remove the first hinge plate from the edge of the door by extracting the screws that hold it there. Lift the plate off the door. It will leave an indentation on the edge of the door where the hinge was inset.
Move the hinge plate so the loose side (that was attached to the jamb) is hanging off the opposite side of the edge as it was before. Move the hinge over along the edge by one hinge length, so it's not sitting over the same inset area as before, but is on flat wood.
Mark around the plate onto the door edge with your pencil, tracing the shape of the plate. Remove the plate. Cut around the pencil mark with your razor, making the cut about 1/8 inch deep.
Chisel out the wood within the cut area, using your chisel and hammer and making it about 1/8 inch deep throughout.
Set the hinge plate back on the edge, in the chiselled-out area, so the plate sits flat in the inset. Sink new hinge screws into the plate to secure it. Repeat the process for each of the other hinges.
Stand the door back in the doorway. Set the loose halves of the hinge plates against the door jamb. Trace around the plates with a pencil, chisel them out, and set the plates back in place, insetting them into the wood. Secure them with hinge screws.
Reverse the door latch and related hardware so it can open from the other side. For most latches, this will mean extracting the screws that hold the knobs in, pulling out the knobs, pulling the latch out through the front edge, turning it, and reinstalling everything in that position.