Composite stratovolcanoes are found at destructive plate margins and have much steeper sides than shield volcanoes. This is because the lava erupted from them is andesitic intermediate and so flows less easily as it is more viscous. Therefore if can not travel as far, resulting in the steep sides of the volcano. An example of this is Mount Fiji and also Mt Etna in Sicily. These therefore have more explosive eruptions as the thicker more viscous lava builds up until a large amount of pressure causes it to erupt. [Third type, plus example]
Calderas are another type and these again have steep sides due to more