An active volcano is a volcano that is currently erupting, or has the potential to erupt in the future. Conventionally it is applied to any that have erupted during the Holocene (the current geologic epoch that began approximately 11,700 years ago). A volcano that is not currently erupting but could erupt in the future is also known as a dormant volcano. Volcanoes that will not erupt again, or is thought to never erupt again, are known as extinct volcanoes.

There are 1,650 potentially active volcanoes around the world, 500 of which have erupted in historical time. Many active volcanoes are located along the Pacific Rim, also known as the Pacific Ring of Fire. An estimated 500 million people live near active volcanoes.

Historical time (or recorded history) is another timeframe for active. The span of recorded history differs from region to region. In China and the Mediterranean, it reaches back nearly 3,000 years, but in the Pacific Northwest of the United States and Canada, it reaches back less than 300 years, and in Hawaii and New Zealand it is only around 200 years. The incomplete Catalogue of the Active Volcanoes of the World, published in parts between 1951 and 1975 by the International Association of Volcanology, uses this definition, by which there are more than 500 active volcanoes. As of March 2021^[update], the Smithsonian Institution's Global Volcanism Program recognizes 560 volcanoes with confirmed historical eruptions.

Countries with the most Holocene volcanoes, according to the Smithsonian Institution's Global Volcanism Program (as of 2023^[update]):

Countries with the most volcanoes active since 1960 (as of 2023^[update]):

As of 2025, the following are considered Earth's most active volcanoes:

Other highly active volcanoes include:

Holocene volcanoes with large populations within 5 km (3.1 mi):