How do the clicks in the Khoisan languages work?

Clicks are non-pulmonic speech sounds produced by closing the mouth and releasing a burst of air from the oral cavity. They are considered 'non-pulmonic' because they do not rely on the lungs' airflow. Instead, the air for a click is produced in the mouth while forming a vacuum with the tongue. Clicks are used contrastively in Khoisan languages, meaning they are phonemic and used to distinguish different words.