If one is speaking or writing to someone, here are the titles you would use:
Mr. (Mister) any man
Miss an unmarried woman
Mrs. (Mistress) a married woman
Ms. When you don't know if a woman is married or unmarried.
Dr. Doctor This is used for medical doctors and also for persons with a PHD degree in any subject.
I thought this might help. Usually we are more informal in America. I want you to just call me Sue, although my title would be Mrs. Sue Petrovski. Before I was married I was Miss Sue Matthews. I married Mr. Rudy Petrovski and when a woman marries she takes his last name. Sometimes I sign myself as
Sue Matthews Petrovski
