"Ms." is a title used before a womans name, much like "Miss" and "Mrs." However, unlike those terms, it doesnt specify whether the woman is married or unmarried. Its used as an equivalent to "Mr." and is a neutral title for women regardless of their marital status, be it married or unmarried. The title "Ms." was invented in the 20th century to refer to a woman whose marital status is unknown to the speaker. It was embraced by the feminist movement as a way of referring to a woman without defining her by her marital status, equivalent to the masculine "Mr.". Despite the period, "Ms." is not an abbreviation for anything. The period is simply there to indicate that it is a valid title for adults to use, like "Mr." or "Mrs.".