Stuttering, sometimes called “stammering,” is a speech disorder in which the normal flow of speech is broken by frequent repetitions (“st-st-stop that”) prolongations (“sssss-stop that”) stopping of sounds and syllables that are abnormal (no sound) or some words proceeded by “um” or “uh.” People who stutter know what they want to say, but have difficulty saying it. People who stutter may also have unusual facial and body movements associated with their effort to speak. In most cases, stuttering may have an impact on at least some daily activities by how the person or others react to the disorder.