Key message
The one idea the audience should understand and remember, even after every supporting detail has faded.
See it
What it is
A key message is the single idea the audience should understand and remember after the details fall away. It is the roof of a message house: supporting claims and proof can sit underneath, but every one of them should make that top idea more believable. A good key message states an audience-relevant claim, not merely the topic being discussed.
Set it before writing a page, launch, interview, speech, or campaign. If the reader saw only the headline and one proof point, the key message tells you what those two pieces must communicate. Test it by asking someone to repeat the point in their own words after one read.
Gotcha: a key message is not a tagline. A tagline is polished public copy; the key message is the strategic sentence that many headlines, talking points, and taglines can express. If it needs 'and' to join two unrelated promises, you probably have two messages and have not chosen.
Ask AI for it
Use the message house technique to produce one key message for [audience] from [positioning], [approved claims], and [evidence]. Write one sentence under 20 words that names the relevant outcome and the reason to believe it. Then add exactly 3 supporting claims and one supplied proof point under each. Reject any version that joins unrelated promises with 'and', sounds like a category label, or could take a competitor's name unchanged. Return the key message first, followed by the message house and a one-sentence recall test.