Volcano classification

One way of classifying volcanoes is by the type of material erupted, which affects the shape of the volcano. If the erupting magma contains a high percentage (65%) of silica the lava is called felsic or acidic or Granitic. Felsic lava tends to be highly viscous (not very fluid) and is pushed up in a blob that solidifies relatively quickly. Viscous lavas tend to form stratovolcanoes. Lassen Peak in California is an example of a stratovolcano formed from felsic lava. This type of volcano has a tendency to explode when erupting, because the viscous lava traps volatiles (gases), and easily plugs. Mount Pelée on the island of Martinique is another example.
If, on the other hand, the magma contains a relatively low percentage of silica, the lava is called mafic or basic or basaltic and will be very fluid as it erupts, capable of flowing for long distances. 'Mafic' is a word referring to the chemical composition of the lava -- it contains higher percentages of magnesium (Mg) and iron (Fe), and correspondingly lower percentages of silica. Due to low viscosity, volatiles are able to escape. A good example of a mafic lava flow is the Great flow produced by an eruptive fissure near the geographical center of Iceland roughly 8,000 years ago; it flowed to the sea, a distance of 130 kilometers, and covered an area of 800 square km. The shield volcanoes forming the islands of Hawaii also produce low-viscosity, mafic lavas. Lavas (and rocks) with particularly high proportion of iron and/or magnesium are called 'ultra-mafic'. A third type of lava that eruptsfrom volcanoes is andesitic, this lava has moderate amounts of silica and a moderate temperature.
Shield volcanoes

Toes of a pāhoehoe advance across a road in Kalapana on the east rift zone of Kīlauea Volcano in Hawai‘i.
Hawaii and Iceland are examples of places where volcanoes extrude huge quantities of lava that gradually build a wide mountain with a shield-like profile. Their lava flows are generally very hot and very fluid, contributing to long flows. The largest lava shield on Earth, Mauna Loa, is 9,000 m tall (it sits on the sea floor), 120 km in diameter and forms part of the Island of Hawaii. Olympus Mons is a shield volcano on Mars, and the tallest mountain in the known solar system. Smaller versions of the "lava shield" include the 'lava dome' (tholoid), 'lava cone', and 'lava mound'.
Cinder cones
Volcanic cones or cinder cones result from eruptions that throw out mostly small pieces of cinder that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 m high. Cinder cones may be associated with other types of volcanoes, or occur on their own.
Stratovolcanoes or composite volcanoes
These are tall conical mountains composed of both lava flows and ejected material, being layered alternatively, which form the strata that give rise to the name. Classic examples include Mt. Fuji in Japan and Mount Mayon in the Philippines. Volcanoes on land often take the form of flat cones, as the expulsions build up over the years, or in short-lived volcanic cones, cinder cones.
Supervolcanoes
"Supervolcano" is the popular term for large volcanoes that usually have a large caldera and can potentially produce devastation on a continental scale and cause major global weather pattern changes. Potential candidates include the Yellowstone Caldera in Yellowstone National Park, the Long Valley Caldera near Mammoth Lakes, California, and Lake Toba, but are hard to identify given that there is no formal definition of the term.