Systematic desensitization is similar to classical conditioning and requires the patient to undergo a series of steps. Patients generally start with various relaxation strategies, such as different imagining techniques, deep breathing, muscle relaxation, and so forth. The second step involves exposure to the fear. Patients are slowly introduced to situations that cause anxiety in small amounts; for instance, a person with a fear of flying might start by simply walking into an airport, then graduate to stepping onto a plane, and other small steps until they have experienced enough exposure to the stimulus that they no longer panic. Basically, the patient and doctor create a "hierarchy" that is similar to a pyramid--the patient rates various aspects of the fear on a scale of 0-100, say, and as a team, the doctor and patient slowly make their way from the bottom (least frightening) to the top (most frightening) of the scale, practicing relaxation techniques and increasing exposure until the fear is extinguished.