Here's why:

* Composite volcanoes are characterized by their steep, cone-shaped profiles, formed by layers of alternating lava flows and volcanic ash.

* Shield volcanoes, on the other hand, have gentle slopes and are formed primarily by fluid lava flows that spread over a large area.

Etna's distinctive cone shape, its history of explosive eruptions producing ash and tephra, and its layers of solidified lava flows all point to it being a composite volcano.