'告诉' (gàosu) is a compound verb meaning 'to tell' or 'to inform'—it conveys the act of communicating information from one person to another. The first character, 告 (gào), originally meant 'to report' or 'to announce', often with a sense of formality or urgency; the second, 诉 (sù), means 'to state' or 'to recount', emphasizing verbal expression. Together, they form a common, neutral-register verb used in everyday spoken and written Chinese for sharing facts, instructions, news, or personal updates.

This verb always requires both a subject (the speaker) and an object (the listener), and it typically takes a direct object indicating what is being told—either a noun phrase ('the news') or a clause introduced by 'that' (expressed with a quoted sentence or using 跟/对 + person + 说 structure when specifying the listener). It is not used for commands or requests, nor does it imply persuasion—just straightforward transmission of information.