Stuttering or dysfluency is characterized by disruptions in the production of speech sounds. Most people produce brief dysfluencies from time to time. Dysfluencies can impede communication when a person produces too many of them. Stuttering frequently includes repetitions of words or parts of words and prolongations of various speech sounds. Speech may be blocked or stopped when the individual's mouth is positioned to say a sound. Interjections such as 'um' or 'like' are also common.