Stuttering is a speech disorder characterized by the frequent repetition of words or parts of words that disrupts the normal flow of speech. Stuttering often begins in childhood and, as such, may be thought of as being a developmental disorder. The precise cause of the disorder is unknown. Stuttering is embarrassing and can cause a sufferer to feel anxiety, distress, and frustration that may later develop into a social phobia. Signs of stuttering include stuttering on certain words, repeating or prolonging certain sounds before the word is said, complete voice blocks, gestures or movements such as jerking the head, licking the lips, nasal snorting, and closing the eyes, and excessive muscle tension in the face or parts of the body. Treatment options include biofeedback, psychotherapy, speech therapy, supportive treatment (not trying to help by filling in words and also providing a non-threatening atmosphere), relaxation therapies, and breath control.