When to use "Mr."?
Always use "Mr." when referring to a man, regardless if he’s married or not. Historically and today, men need not worry about marriage changing the way they’re addressed.
What titles have a period after "Mr."?
American titles include a period after: Mr., Mrs., Ms.
How to use titles for men and women?
A man always goes by "Mr." or "Mister" regardless of his marital status, whereas how you refer to a woman can offend some, so it’s best to ask if you’re unsure.
Do widowed women still refer to themselves as "Mrs."?
As well as being used for married women, some widowed or divorced women still refer to themselves as "Mrs." You can’t assume that someone using the title "Mrs." has a spouse ; they just might want to still be referred to as "Mrs." Especially for older, widowed women, it might offend them if you addressed them as "Ms."