Hoarseness is the colloquial expression for dysphonia ; these terms are often used interchangeably in medicine to refer to altered voice quality. Hoarseness may be both a symptom and a sign of dysfunction of the phonatory apparatus. It is never a diagnosis, despite having a corresponding International Classification of Diseases code and sometimes serving as such for purposes of administrative convenience. The same anatomical and physiological features that make the vocal folds uniquely suited for the high-speed vibration necessary for sound production render them exquisitely sensitive to a wide range of abnormalities. The breadth of pathologic conditions that can cause hoarseness makes a unified overview a challenge; hoarseness is simply not a homogeneous category after the initial laryngoscopy. Moreover, the available literature predominantly focuses on specific diagnoses rather than on hoarseness as a whole, so scant published data exist to support an evidence-based approach. Nevertheless, certain unifying principles exist.