A cognitive-behavioral therapy technique for treating phobias and other fear- and anxiety-related problems, exposure therapy presents the patient with progressively stronger, more frightening stimuli at his or her own pace until he or she habituates (is desensitized) to the stimulus.
Example: A child with a debilitating fear of spiders progresses from looking at a picture of a spider, to sitting in the same room as a caged spider, to holding a loose spider with minimal anxiety.
I think this website is a great resource to learn more about the procedure: http://www.wisegeek.com/what-is-exposure-therapy.htm
Fournier, G. (2010). Exposure Therapy. Psych Central. Retrieved on May 6, 2015, from http://psychcentral.com/encyclopedia/2009/exposure-therapy/