Gaslighting is a form of emotional abuse. It is a form of manipulation that makes somebody question their own memories and feelings so that they start to doubt themselves. It may involve someone saying things that are not true or denying things that have happened, to try and make the other person feel confused or ashamed. For example, an abuser may tell the person that something didn't happen, even though it did. This can make the person start to think that they are imagining things or questioning the reality of what actually happened.