An air scenting dog works by picking up human scent that is primarily airborne (hence the term).  Once this dog finds the scent cone, he follows the scent to its source.  this dog may or may not be trained as scent discriminating.  Some dogs are trained to indicate any source of human scent in a given area.  This is ideal in an area of wilderness where few humans are present and one must identify anyone in the area.  However, for urban and suburban regions, heavily traveled wilderness, back-country, a scent discriminating dog may work better.  This dog picks up the scent of a missing person off of an article of clothing or some other personal possession, and is able to look for that individual, while ignoring all others.  He usually works off-lead, ranging a good distance away from the handler.  However, he must always be responsive to the handler's commands while working a field and must possess a strong indication to notify the handler of a find.

An alert is a visual cue as perceived by the handler that her dog has detected the scent of its target.  The dog's body language is the "alert".  Some dogs have very subtle alerts requiring the handler to be in-tune to her every mannerism and each degree of her movement, while others telegraph their alerts so greatly that even a novice would be able to tell that the dog has located a scent.  The term "alert" is often used interchangeably with the term "indication", such as in the term "passive alert" or "bark alert".

This is a dog that has been trained in the specialty of locating the scent of decomposing human tissue.  The dog may be asked to locate a whole corpse (as in a missing person presumed dead), or only body parts from catastrophic trauma such as natural disasters, or foul play with subsequent body dismemberment.  A cadaver dog generally has first mastered other forms of searches before being trained to the rigorous demands of this type of work.

A tracking dog works in a tracing harness and line.  This dog is best used when the last whereabouts of the missing person is known.  This location is known as the point last seen, or PLS.  The dog is brought into the vicinity of the PLS in the hopes that she will be able to pick up the track of the missing person.  A scent article may be helpful here, as this dog is scent-discriminating.  The dog will track with its nose to the ground, primarily focusing its attention on contact and ground scent.

Scent molecules disperse outwards from their source in a conical pattern, forming a scent cone downwind of the subject.  An air scenting dog normally works across or into the wind until he locates the scent cone.  At this point the dog will give an alert, and will begin working his way into the funnel of the cone until he reaches the source, which is the quarry.  The dog will then alert his handler of the find.

The ability of dogs to differentiate one scent source from another is called scent discrimination.  It is fundamentally necessary in the search dog, as it is this ability which enables a tracking/trailing dog to home in on its quarry, while ignoring all other cross paths of humans or animals.  It enables the air scenting dog to search out and identify to her handler the source of the scent article (or vice versa in evidence or article search), even in an area contaminated by other human scent, and even if that person is standing among a group of other individuals.

An indication is most often a trained response by which a dog notifies its handler of a find.  It is the dog's way of telling its handler.  "Yeah!  I found it!"  Quite often the term is used interchangeably with the term "alert".  There are bark indications, passive indications (such as when the dog lies down or sits), body slams Bringsels, and recall-refunds.

For many search managers, the concept of a water search with dogs sounds like an impossibility.  After all, we have always been told that the best way to elude capture by a man tracking team with bloodhounds is to run into the river and hide.  But water is not an impenetrable, sterile medium.  We should consider it more as a porous organism and visualize that there is constant movement within and throughout any body of water.  Now let's look at the basic structure of scent.  Scent is made up of several components:  skin particles, perspiration, skin oils, sweat glands, and other gaseous components.  Further, as these components break down during decomposition, bacterial action increases scent production.  When the body of a deceased person is under water, these components rise (or raft) up through the water until they reach the surface.  From there, the scent particles are dissipated by the breeze and the current.  This action occurs at varying rates, depending upon several factors:  water temperature, depth of submersion, thermo cline, water currents and speed, and wind velocity.  A dog trained in water search is able to detect these scent particles and indicate to the handler the direction to the source in the same manner as an air scenting dog would indicate scent during a wilderness or cadaver search.  These dogs can be deployed from shore, but ideally work from a boat with an experienced handler.