"Stuttering is a communication disorder that affects the fluency of speech......."

What is stuttering?
Stuttering is a communication disorder that affects the fluency of speech. It begins during childhood and, in some cases, persists throughout the life span. The disorder is characterized by disruptions in the production of speech sounds. Speech-language pathologists refer to these disruptions as "disfluencies." Most speakers produce brief disfluencies in speech from time to time. For instance, some words are repeated and others are preceded by interjections such as "um." Disfluencies are not necessarily problematic; however, they can impede communication when a speaker produces too many of them or does not resolve them promptly.

Stuttered speech often includes repetitions of words or parts of words, as well as prolongations of speech sounds. The frequency of these disfluencies among persons who stutter tends to be much greater than it is for the general population. Some speakers who stutter exhibit excessive physical tension in the speech musculature or appear to be "out of breath" when talking. At times, the forward flow of speech may become completely stopped or blocked. That is, the speaker may position the mouth to say a sound, sometimes for several seconds, with little or no sound forthcoming. Finally, after some effort, the speaker completes the word. Interjections such as "um" or "like" can be symptomatic of the disorder, as well, particularly when the interjections contain repeated ("u- um- um") or prolonged ("uuuum") speech sounds or when they are used intentionally to delay the initiation of a word the speaker expects to "get stuck on."