"Mr." is an abbreviation for "Mister", which is a title used before a man's name.

"Mister" is derived from the Old Engpsh "master", which was originally used to address men of higher social status or those in positions of authority. Over time, it evolved into the modern "Mister" and was commonly used as a title of respect for men, regardless of their marital status.

Example sentences:

Mr. Smith is a doctor.
史密斯先生是一名医生。
Can I speak to Mr. Johnson, please?
请问我可以和约翰逊先生通话吗？
Mr. and Mrs. Brown are going on a trip.
布朗夫妇正在出去旅行。

Note: The title "Mr." is typically only used in Engpsh-speaking countries and is not commonly used in other parts of the world.