Fluency is the aspect of speech production that refers to continuity, smoothness, rate, and effort. Stuttering, the most common fluency disorder, is an interruption in the flow of speaking characterized by repetitions (sounds, syllables, words, phrases), sound prolongations, blocks, interjections, and revisions, which may affect the rate and rhythm of speech. Stuttering is a neurodevelopmental speech disorder. Its onset usually occurs between the ages of 2 and 5 years. The etiology is not fully understood but recent research suggests that the factors that contribute to the emergence of stuttering are a combination of genetic and environmental.  For many children who stutter, spontaneous recovery will occur before puberty. If a child has been stuttering longer than 6 months, or if the stuttering has worsened, they may be less likely to outgrow it on their own. An evaluation can help determine whether therapy is needed.  Stuttering therapy usually means learning to talk in an easier manner, and to build positive emotions, and attitudes about talking. As a result, length and type of therapy can vary greatly depending on a person’s individual needs.