Smell is an important factor in a wolf's life, so a good sense of smell is necessary for survival. They use it for tracking, hunting, communication and a lot more. Under good circumstances, a wolf can sense prey 3 kilometers away. The wolf's equivalent to our fingerprints are two glands of smell, one at the back and one at the rectum. The secrete from these two glands is different for every wolf.
Wolves also use smell for marking out borderlines and paths in their territory.
They mark with urine, excrement or by digging in the ground. The distance between two marks is normally 100m, but the distance is smaller near borderlines next to other wolves. Their eyesight is terrific and a good aid in hunting, etc. Their eyes, like almost all predators, point forward with a sight-field of nearly 180 degrees. Their good hearing is used for hunting, communication etc.