their stuttering. People who stutter often find that their stuttering fluctuates and that they have "good" days, "bad" days and "stutter-free" days. The times in which their stuttering fluctuates can be random. Although the exact etiology, or cause, of stuttering is unknown, both genetics and neurophysiology are thought to contribute. There are many treatments and speech therapy techniques available that may help decrease speech disfluency in some people who stutter to the point where an untrained ear cannot identify a problem; however, there is essentially no cure for the disorder at present. The severity of the person's stuttering would correspond to the amount of speech therapy needed to decrease disfluency. For severe stuttering, long-term therapy and hard work is required to decrease disfluency. Characteristics Common behaviors Common stuttering behaviors are observable signs of speech disfluencies, for example: repeating sounds, syllables, words or phrases, silent blocks and prolongation of sounds. These differ from the normal disfluencies found in all speakers in that stuttering disfluencies may last longer, occur more frequently, and are produced with more effort and strain. Stuttering disfluencies also vary in quality: common disfluencies tend to be repeated movements, fixed postures, or superfluous behaviors. Each of these three categories is composed of subgroups of stutters and disfluencies. Repeated movements Syllable repetition—a single syllable word is repeated (for example: on—on—on a chair) or a part of a word which is still a full syllable such as "un—un—under the ..." and "o—o—open". Incomplete syllable repetition—an incomplete syllable is repeated, such as a consonant without a vowel, for example, "c—c—c—cold". Multi-syllable repetition—more than one syllable such as a whole word, or more than one word is repeated, such as "I know—I know—I know a lot of information." Fixed postures With audible airflow—prolongation of a sound occurs such as "mmmmmmmmmom". Without audible airflow—such as a block of speech or a tense pause where nothing is said despite efforts. Superfluous behaviors Verbal—this includes an interjection such as an unnecessary uh or um as well as revisions, such as going back and correcting one's initial statements such as "I—My girlfriend ...", where the I has been corrected to the word my. Nonverbal—these are visible or audible speech behaviors, such as lip smacking, throat clearing, head thrusting, etc., usually representing an effort to break through or circumvent a block or stuttering loop. Variability The severity of a stutter is often not constant even for people who