What plays a major part in determining the form of a volcano?

The form of a volcano is primarily determined by the composition and viscosity of the magma, as well as the eruption style. Magma that is low in viscosity, like basalt, allows for fluid lava flows, leading to broad, shield-shaped volcanoes. In contrast, more viscous magma, such as andesite or rhyolite, tends to produce explosive eruptions and builds steep-sided stratovolcanoes. Additionally, the presence of gas in the magma influences the eruption dynamics, further shaping the volcano's structure.