In hypnosis, there are a number of “power” words that can and are used to enhance the trance process and because they are so powerful, it means that when we use them together their power multiplies which means that the hypnotic trance being generated and enjoyed by the client becomes even deeper and the changes made, whatever those changes are that their powerful unconscious mind chooses because your unconscious mind is able to perform this, as the client enjoys a deeper level of trance becomes even more profound.
I read an interesting article on New Scientist today describing how new research is suggesting that those who are un-hypnotisable may have a more balanced brain (between left and right hemispheres) than those that are highly susceptible!
There is a kind of standard statistic in hypnosis that (whether through suggestion or genuine experience) most hypnotists will agree on:
About 20% of the population is highly susceptible
About 60% of the population can be hypnotised
About 20% of the population cannot be hypnotised