[1] After its replacement in common speech by Mister, Master was retained as a form of address only for boys who had not yet entered society.
The use of Master as a prefixed title is, according to Leslie Dunkling, "a way of addressing politely a boy ... too young to be called 'Mister'.
[3] Master was used sometimes, especially up to the late 19th century, to describe the male head of a large estate or household who employed domestic workers.
Nancy Tuckerman, in the Amy Vanderbilt Complete Book of Etiquette, writes that in the United States, unlike the UK, a boy can be addressed as Master only until age 12, then is addressed only by his name with no title until he turns 18, when he takes the title of Mr.,[5]: 662 although it is not improper to use Mr. if he is slightly younger.
Master is also frequently used (along with feminine Mistress or Domina) in the BDSM community[6] as a self-identifier by dominants, and by submissives in addressing them, especially in master/slave-roleplay relationships.