Mr.: Any man, single or married, not using a professional title

Miss: Any woman who has never been married or any woman whose marriage has been annulled.

Ms.: Any single woman over the age of 21, or any woman using a professional name regardless of

marital status, or any divorced or widowed woman with no children.

Ms. is not for use on formal stationery and is not an abbreviation.

Mrs.: Any legally married woman, or any divorced woman who has retained her married name, or a widowed woman who has not remarried.

Dr.: Any person holding a professional medical degree. "Dr." is not the same as

a Ph.D.