A vent is an opening that allows air, smoke, or gas to enter or leave a closed space. It can also refer to an opportunity or means of escape, passage, or release. The term can be used as a noun or a verb. As a verb, "to vent" means to give free play or expression to an emotion or passion, or to give public utterance to ones opinions. As a noun, "vent" can refer to:

• An opening for the escape of a gas or liquid or for the relief of pressure: This can include the external opening of the rectum or cloaca, an opening at the breech of a muzzle-loading gun through which fire is touched to the powder, or a slit in a garment.

• A means of escape, passage, or release: This can include an outlet or a back vent that allows air to flow.

In the context of volcanoes, vents are the locations from which lava flows and pyroclastic material are erupted.