Speech sounds divide roughly into those with open airflow and those with constriction. A consonant is a speech sound produced with a partial or complete obstruction of the airstream in the vocal tract.

Consonants are classified by place of articulation, manner of articulation, and voicing. Stops, fricatives, nasals, and liquids illustrate different manners. Languages select different inventories from the wide phonetic possibilities humans can produce.

Consonant clusters, assimilation rules, and syllable-structure constraints shape phonotactics. Children acquire certain consonants later than others, which shows up in developmental speech patterns. Phonetic transcription relies on precise consonant symbols to capture contrasts that ordinary orthography misses.

• Speech sound with obstructed airflow
• Described by place, manner, and voicing
• Inventory differs across languages
• Central to phonotactics and acquisition studies