While these apps are generally safe, they have not been scientifically tested for efficacy. Some of them also incorporate visual elements and other sound effects.
Hypnosis apps typically use audio tracks that may include vocals and music. Practicing self-hypnosis is very similar to meditation, but self-hypnosis is more goal-oriented and puts you in a trance-like state instead of being present. Hypnosis might also help with quitting smoking or drinking alcohol, as well as weight loss, but more research is needed and long-term results are unknown. However, hypnosis is not meant to be a form of entertainment: The technique can help reduce pain, depression, anxiety, and phobias.
When you hear the term hypnosis, you might think of dramatized stage acts or movie scenes.