Both the titles Miss and Ms. can be used for a woman who is unmarried or whose marital status is not known. Whether to use the title Miss. or Ms., depends on the person being addressed. When in doubt, use the title Ms.; like Mr., as it makes the marital status irrelevant in a way that Miss does not. Use of Mr. The title Mr. is used for a man. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.