Polite asking: xin + verb

Xin means "ask for", and in front of a verb it makes what you say humble and polite, a little like "may I" or "allow me". You'll know it from set phrases: Xin lỗi (sorry, excuse me; literally "ask forgiveness"), Xin cảm ơn (thank you, formally) and Xin chào (hello, formally).

Xin lỗi is everyday, but for hello and thanks people usually just say Chào anh or Cảm ơn chị; Xin chào sounds like a textbook or an announcement. You'll meet xin most in formal speech, notices and service: Xin cảm ơn quý khách. Thank you for your custom. On signs and in announcements, xin (often with vui lòng) asks others politely: Xin vui lòng không hút thuốc. Please don't smoke.

Before a noun, xin is the verb "ask for", and in daily speech it usually follows cho em: Cho em xin cái muỗng. Could I have a spoon, please? (in Hà Nội, cái thìa). Xin phép asks permission: Em xin phép về trước. Excuse me, I'll head off first.

Cho em on its own is the everyday way to ask for something; adding xin makes it humbler. Mời is different: it invites someone else to do something, as in Mời anh ngồi, please have a seat.