Final answer:
Volcanoes grow through eruptions that deposit lava and tephra. A conduit allows magma to rise to the surface, and tephra consists of ejected volcanic fragments.
Step-by-step explanation:
Volcanoes grow as material from deep within the Earth, primarily molten rock known as magma, rises to the surface and solidifies. This process occurs during volcanic eruptions, where magma exits through a conduit, a pipe-like structure leading from the magma chamber to the surface. When eruptions are explosive, they eject various fragments called tephra, which can include ash, lapilli, and volcanic bombs, depending on their size. Over time, successive eruptions deposit layers of lava and tephra around the vent, gradually building up the volcano's shape and size.