Mr. (or Mr) is a social title used for a man. It is an abbreviation of Mister, though it is almost never spelt out in normal usage.

Mister is an alteration of Master; the equivalent female titles, Mrs., Miss, and Ms., are variants of Mistress. After the development of the word Mister for adult males, the title Master was retained and used for boys and young men. In some societies, this is now rare or considered affected, though more acceptable in Britain and still used in conservative enclaves in Africa, Australia, India and the United States. See more at master.

In direct address, Mr. is usually used with the last name only ("May I help you, Mr. Ericson?"). In indirect speech, it can be used with either the last name or the full name ("This is Mr. James Ericson." "Would you please help Mr. Ericson?") On envelopes, it is usually used with the full name.

The title of Mr., like any other title, is a term of respect, and therefore the use of Mr. to introduce or refer to oneself (as in "my name is Mr. Smith") is considered somewhat affected in conventional UK protocol, although such usage is becoming increasingly common in Britain.

In the United Kingdom, most Commonwealth countries and Ireland, a full stop (in the US a period) does not usually follow the abbreviated form: "I saw Mr Brown at the office talking to Mrs Price."

In US English the title "mister" is sometimes used informally by itself in direct address ("Are you alright, mister?"). In formal usage, the title sir is used ("May I help you, sir?)".

Other usages

In some areas, notably the American South, Mr. is sometimes used with only the first name to indicate a mixture of familiarity and respect.

In past centuries, Mr. was used with a first name to distinguish among family members who might otherwise be confused in conversation: Mr. Smith would be the eldest present; younger brothers or cousins were then referred to as Mr. James Smith and Mr. Robert Smith and so on. Such usage survives in family-owned business or when domestic servants are referring to adult male family members with the same surname: Mr. Robert and Mr. Richard will be out this evening, but Mr. Edward is dining in. Such usuage is rare.

The rare plural of Mr. is Messrs.: pronounced "messers", an abbreviation for the French messieurs.

Professional titles

"Mr." can be combined with certain titles (Mr. President, Mr. Speaker, Mr. Justice). The female equivalent is Madam. All of these except Mr. Justice are used in direct address and without the name. The title Mr. Justice Krever is not used in direct address.

In the United States Supreme Court, instead of Mr. or Madam Justice, the title is simply Justice.

In the Courts of England and Wales, Judges of the High Court are called, for example Mr Justice Crane. Where a forename is necessary to avoid ambiguity it is always used, for example Mr Justice Robert Goff to distinguish from a predecessor Mr Justice Goff. The female equivalent is Mrs Justice Hallett, not Madam Justice Hallett. In court, they are addressed as My Lord or My Lady. When more than one judge is sitting and one needs to be specific, one would refer t

In the United Kingdom, male medical practioners who have been admitted to the Royal Surgical Colleges of Great Britain and Ireland discontinue use of the "doctor" title and revert back to using mister. (Females in a similar position revert back to using the title Miss, Mrs. or Ms., depending on martial status and preference)

Marital status

Since the term Mr. does not indicate whether a man is married or not, many feminists believed that a woman's title should not indicate marital status either. For this reason, the title Ms. was advocated as an equivalent to Mr., particularly in business usage. The original female title, Mistress, did not indicate marital status and no distinction was made until the advent of the diminutive Miss for an unmarried woman in the Victorian Era. Thereafter the title for a married woman became Mrs..

In several other European languages, the title used for married women, such as Madame, Senora, or Frau, is the direct feminine equivalent of the title used for men; the title for unmarried women is a diminutive: Mademoiselle, Senorita, or Fräulein. For this reason, usage has shifted towards using the married title as the default for all women in professional usage.

Ambrose Bierce once satirically proposed that, as a parallel to Miss, the title of unmarried men should be Mush.