1 2 3
Mr. is the old style, Mr is the newer and more common style.

The accepted rule now is that if the last letter of the full word is the same as the last letter of the contraction 9shortened word) then no full stop is needed.

So Mr is a contraction of Mister so no full stop. However Rev. is a contraction of Reverend so a full stop is needed.

hope it helps.
Yes. I've learnt this while doing MBA at XLRI from the legendary Prof. Jesurajan who taught Managerial Communication. I believe most XL alumni would remember this point.
(XLRI School of Business, Jamshedpur is a premier B-School in India run by Society of Jesuits)
Teachers: We supply a list of EFL job vacancies
So confusing, because it is the other way around in my mother tounge.

Oddly enough some textbooks in Japan teach AmE, but then use Mr and Mrs

means Miss but in short form.

Students: We have free audio pronunciation exercises.

Hello. I hope you will see this comment.Maybe I am to late to write this but i want to help you. In Us English, we use " Mr. "

But in UK English we use " Mr "