"Bow River Banff" is Copyrighted by Flickr user: ahisgett (Tony Hisgett) under the Creative Commons Attribution license.
Basics
Banff National Park expects all visitors to clean up after themselves, to put out campfires promptly, to stow their garbage, and to avoid defacing or damaging any areas in the park.
Fees
The park charges an entry fee in order to help pay for vital services. It's fairly inexpensive--equal to the price of a movie ticket or thereabouts--and annual passes are available at a discount rate.
Weather
Certain areas may be closed during inclement weather, and the park takes a "you're on your own" policy towards those who wish to hike or climb in snow or rain.
Custodial Groups
Custodial groups traveling in the park as part of a field trip need to have a permit to enter certain challenging areas of the park, and are banned from traveling in more hazardous areas.
Bears
Banff National Park has a large bear population, and they may come down into campgrounds in search of food. All food in the park should be stored in bear-proof containers, and visitors should watch for areas of the park that are closed because of bear sightings.