Since the question has come up a few times lately, I found a visual to help some of you out. Another kind gesture is to give the person going up hill the right-of-way. Gravity is working against them, and if they are carrying gear it's obviously worse. If you're not sure what to do just step to the side of trail, and let them pass. Being courteous isn't that hard. The roads are bad enough, let's not make the trails the same way. Almost forgot, pick up your dogs poo, and don't cut the switchbacks!!!