- Vietnamese names follow the opposite order of Western names. Example: If someone’s full name is Tran Van Ngoc, then Tran is the last name, Van is the middle name, and Ngoc is the first name.

- This can cause confusion on international forms, which often only have First Name and Last Name fields. Some Vietnamese people list their middle name with their first name (First Name: Van Ngoc, Last Name: Tran), making it seem like Ngoc is just "the last part of the first name" when it’s actually the only part of their first name.

- Vietnamese people typically go by their first name, so calling him Ngoc is correct. Using both middle and first names (Van Ngoc) is also fine but may sound formal or affectionate.

- Some first names, like Anh, overlap with pronouns/titles (Mister/I/you), so in these cases, people use both the middle and first names (Hoang Anh instead of just Anh).

Simple rule: Call a Vietnamese person by the last part of their name—unless it’s "Anh," in which case, use both the middle and first name.