It is used by people who sell products, attorneys, and most commonly by mental health therapists. I am a licensed psychologist and the Director of the Counseling Center at Woodbury University. A psychologist is counselor, and a whole lot more.
Psychologists focus on the total mental health needs of their clients.
There are many reasons one could see a psychologist. Generally, when you notice changes in your mood or behavior, or wish your life were more satisfying, are good times to see one. Also, when you feel helpless, blue, nervous, stressed, angry, overwhelmed, or just have trouble making a decision. For example, financial aid counselors may give you advice on the best methods to approach your college funding and an admissions counselor may help you with the application process to the university. Psychologists in general are on the forefront of research studies on depression, stress reduction, pain control, substance abuse treatment, anxiety, and phobias.