Volcanoes are divided into three types on the basis of periodicity of eruption and interval period between two eruptions of volcano. Such as Active, Dormant and Extinct.
This are which constantly ejects lava, gases, ashes and fragmental materials. Most of this volcanoes are found along the mid oceanic ridges representing divergent plate margins and convergent plate margins. Mt. Enta and Stromboli of the Mediterranean sea are the most significant example of this category.
This type of volcanoes are those which become quiet after their eruptions for some time and there are no indications for future eruption but suddenly they erupt very violently and cause enormous damage to human health and wealth. Visuvious volcano is the best example.
This volcanoes are considered extinct when there are no indications of further eruption. The crater is filled up with water and lakes are found. Mt. Kenya is the best example.