A post-hypnotic suggestion is exactly like a hypnotic suggestion, but the subject is told to act it out after he has returned to his normal state of mind. Post-hypnotic suggestions are commonly used in hypnosis, here are some examples:

• As a convincer of the state of trance
• To let the client experience a feeling of comfort when returning from the trance state
• To strengthen the suggestions done in hypnosis
• For entertainment purposes.

Convincers are used by the hypnotist to convice the client that he was actually in a different state of mind. Convincers can be as simple as "After you wake up from trance you will experience the color red everywhere as you have never experienced it before". This will be a very simple yet powerful way to convince the subject of the powers of his subconscious mind.

When the trance state is terminated most hypnotists offer some post-hypnotic suggestions that has the purpose of letting the client experience a feeling of comfort when waking up. There isn't really any reason why this shouldn't be done, as there is no harm in feeling comfortable, even if it's for absolutely no reason.

With post-hypnotic suggestions a clients unconscious mind can be asked to act out on some cue. This cue can be something that the hypnotist is sure that the client will encounter and therefore suggest a very ressourceful state of mind, when the client encounters this.

Stage hypnotists use post-hypnotic suggestions through the entire show. While the subjects on stage are hypnotized he will typically give them suggestions to act out a certain behaviour on a cue. It could be something like "Every time you hear me use the word hypnosis, you will stand up and scream HELLO". The subject is then woken from the trance, and seeminly in a waking state, he will scream "HELLO" every time the hypnotist use the word hypnosis. Some stage hypnotists chain this with other subjects, that are cued to do something on the basis of another subjects behaviour.

It's important that you know, that nobody can install a post-hypnotic suggestion that you don't accept. For more info on this, read "can a hypnotist make me commit a bank robbery".