What is a volcanic crater?

Crater is a general term for a depression at or near a volcanic vent, often created by explosive eruptions that blast away rock or by the collapse of material around the opening. Many active volcanoes have summit craters where lava, gas, or ash may emerge. Some craters hold crater lakes, while others remain dry and steaming. The size of a crater can range from a few meters to several kilometers depending on the volcano and eruption history. Although people sometimes confuse craters with calderas, a caldera is usually much larger and formed by a broader collapse.