The vietnamese society is structured to age. So their mode of address is rather complicated.
A Vietnamese name is ordered as follows: family name, surname and one’s own name. For example: Nguyễn Quốc Hoàn, “Nguyễn” is the family name. “Quốc” surname and “Hoàn” his own name. In every day life, one is called by his own name. In case there are more than one same names in an addressing situation, e.g in the same class, one is called by his/her surname and own name together. For example: Hoa Mai, Ngọc Trúc, Thanh Trúc. Note that “Thị” is the popular surname for female and “Văn” for male.
Infomal situation one is called by one’s own name or surname and own name togetther.
Informal situation for old people. They are addressed by “Cụ + name” both for female and male. For example: “Cụ Vinh”, “Cụ Trúc”…
“Bác (Chú) + name” is applied to middle-aged person. For example: “Bác Nhân”, “Chú Tuấn”…
Formely, “Ông + name” for example: “Ông Hai” is used with respect, but it is now less used. Nowadays “Ông” is used not to show respect, but as a mark of e quality and friendliness.
Schoolchildren and students alike call their men-teacher “thầy”, their women-teachers “Cô” without adding names. They address them “Thưa thầy”, “Thưa cố”.
Boys and girl are addressed by their elderly people as “cậu + name” and “cô + name” respectivety.
Young man and young woman are addressed as “anh + name” and “chị + name” respectively.
The administrative titles like “Giám đốc” (director). “Thứ trưởng” (vice ministrer) ect, are used as a form of address.
Professional titles like “Tiến sĩ” (doctor) or “Giáo sư” (professor) are not used a form of address. But “Bác sĩ” (doctor of medicine) can be used alone or with his/her name. For example: “Thưa bác sĩ” or “Thưa bác sĩ Phương”
The Vietnamese are in a habit of giving title to the wife of a man in administrative position, for example, “Bà giám đốc”.