Suggestion
A suggestion is a proposal the nervous system is invited to act on — not an order, not a spell, and not a thought planted against someone's will. In hypnosis it is the working unit. Trance is only the room. What happens in the room is suggestion.
That one sentence is the whole field, turned the right way up. Most arguments about hypnosis are arguments about suggestion that nobody named.
What it is not
It is not a command that bypasses the person. A suggestion that lands has been taken — expected, allowed, or at least not refused. The ones that fail are usually the ones delivered as if refusal were impossible.
It is not the same as belief. Someone can accept a suggestion for the length of a session ("your hand is heavy") without rewriting what they think about the world. And it is not the same as information. "The window is open" is a report. "The window can stay open while you listen" is a suggestion: it points attention and asks for a small yes.
Direct suggestions name the thing ("let the shoulders drop"). Indirect ones point beside it ("some people notice the shoulders have already started"). Neither is morally cleaner. Indirect language just leaves more room for the person to arrive by themselves. In this house that room is the default. The sharp form exists; it is a register, not a personality.
How a suggestion actually works
Four conditions, and they are ordinary.
Attention. Something has to be listening. That is what trance and induction are for — not magic, just a narrower channel.
Expectancy. What someone believes is about to happen shapes what they notice. This is the same machinery that makes a placebo do real work, and it is why a two-minute honest frame beats a twenty-minute script.
Permission. A suggestion that the person has decided not to take does not take. Covert work fails as craft before it fails as ethics: without the yes, there is no load on the line. See consent.
Ratification. You name what is already happening. "The lids are heavier" said a half-second after they are. Each small truth buys credit for the next proposal. That is ideomotor honesty, not theatre.
A post-hypnotic suggestion is the same object with a delay and a trigger. It needs a scope and an end, or it is not a suggestion — it is leftover wiring. How to set and lift that wiring is a guide, not this page.
Autosuggestion
Said to yourself, a suggestion is still a suggestion. Self-hypnosis is the craft of becoming both speaker and listener without the second voice. Coué's old line — that imagination outruns will — is a useful caution, not a law of physics. Repeating a sentence you do not mean just trains you to ignore yourself.
Where the claims stop
Suggestion can change what is noticed, how strongly a sensation is weighted, how easily a movement starts or waits. It does not install beliefs the person has refused. It does not replace medical treatment. It does not make anyone love you, obey you, or forget who they are. Those sentences belong on safety and they belong here, because the word is constantly asked to carry more than it can.
Between consenting adults the same unit is what erotic hypnosis is made of. The content changes. The mechanics do not. The written forms live in the books.
See also
Trance · Induction · Post-hypnotic suggestion · Consent · How hypnosis works
FAQ
What is a suggestion in hypnosis? A proposal attention is invited to act on. Trance makes the proposal easier to take. It does not force it.
Are hypnotic suggestions permanent? No. Anything set can be lifted, and anything without an end date is unfinished work. Scope and expiry are part of the suggestion, not extras.
What is the difference between a suggestion and a command? A command assumes compliance. A suggestion leaves the taking visible. In practice the voice can be firm either way; the difference is whether refusal still has a place to stand.
Can you suggest something someone does not want? You can say the words. Without permission they bounce, or they produce politeness. That is not depth. It is a failed proposal.