From Bushwalk Australia
Minimum Impact Bushwalking. It essentially means leaving the bush as undisturbed and unaffected by your presence as possible. It is imperative that all new and experienced bushwalkers and other bush users practice this philosophy, to safeguard our remaining wild places against degradation. A few of the basic MIB principles are using fuel stoves instead of camp fires, using existing campsites, packing out your rubbish and staying on formed tracks where they exist. MIB principles have been adopted as policy by many land managers. For further details see this Minimal Impact Activities document from Parks and Wildlife Service Tasmania.