How are igneous rocks formed?

Igneous rocks are formed by magma from the molten interior of the Earth. When magma erupts it cools to form volcanic landforms. If magma cools inside the Earth it forms intrusive rock, which may later be exposed by erosion and weathering.

Examples of igneous rocks include basalt and granite.

Giants Causeway which is made of basalt, an igneous rock
Granite rocks, which is an igneous rock, on a hill side