The three stages of a volcano's life cycle are dormant, active and extinct. However, the definitions of these life stages are not always set in stone, according to Oregon State University.
A dormant volcano is expected to erupt again but has been inactive over the past 10,000 years. An active volcano has erupted in the past 10,000 years, or since the most recent ice age. An extinct volcano is one that is not expected to erupt again. Eruption can be counted as yet another stage, but eruption still falls under the definition of an active volcano, according to Volcano Discovery.