cho hay

Cho hay serves two main roles depending on the context. It is highly synonymous with cho biết (to make known / to inform) when reporting information. However, while cho biết is flexible enough to take simple factual data points as objects (e.g., cho biết tên) and a wide range of inanimate subjects (e.g., biểu đồ cho biết), cho hay is primarily used with human, organizational, or informational sources (like reports, studies, or newspapers) to introduce reporting clauses or quotes. While it cannot take simple factual data points as objects, it can take noun objects meaning 'news' or 'story' (e.g., tin này, chuyện đó), especially in the colloquial register.

1. Formal News Register:
In the news register, it carries an objective tone meaning 'to state' or 'to inform.' It is heavily used to introduce both indirect reports and direct quotes.
Syntax:
• [Source] + cho hay + [rằng/là] + [Reported Information]
• [Source] + cho hay: "[Direct Quote]"

2. Casual Everyday Speech:
In colloquial Vietnamese, particularly in Southern dialects, it is extremely common and means 'to let [someone] know.' In this usage, an indirect object is often inserted between the words, and the phrase is usually preceded by a verb of communication like nói, báo, or kể (e.g., kể cho tui hay chuyện đó, báo cho tôi hay tin này). The indirect object is frequently dropped if it is obvious from context (e.g., báo cho hay).
Syntax: [Verb of communication] + cho + [Person] + hay + [Noun/Clause].

Important Distinction:
Do not confuse this with the causative structure cho + the adjective hay (meaning 'good' or 'interesting'), as in viết cho hay (write well). In cho hay, hay is an older verb meaning 'to know.' You can see this same root in other common phrases like hay tin (to hear the news) or không hay biết gì (to be completely unaware). The exact equivalence of cho biết and cho hay in traditional speech is beautifully illustrated in the proverb Đi thưa cho biết, về trình cho hay (When leaving, announce it so they know; when returning, report it so they are informed).

Classical Usage:
In classical literature, cho hay can also appear at the beginning of a sentence meaning 'Thus it is known that...' or 'In conclusion.' It typically introduces a moral lesson or proverb summarizing the preceding narrative. A famous example is from Nguyễn Du's Truyện Kiều: Cho hay muôn sự tại trời (Clearly, all things depend on Heaven / It is thus known that all things are in Heaven's hands).