Igneous activity refers to the processes that involve the formation and movement of molten rock, known as magma, beneath the Earth's surface. When magma rises and erupts through the Earth's crust, it becomes lava, leading to the creation of various types of igneous rocks. This activity is primarily driven by the heat from the Earth's interior, which can be caused by radioactive decay and residual heat from the planet's formation. There are two main types of igneous activity: intrusive and extrusive. Intrusive activity occurs when magma cools and solidifies below the surface, forming rocks like granite. In contrast, extrusive activity happens when lava erupts onto the surface, cooling quickly to form rocks such as basalt. Both processes play a crucial role in shaping the Earth's landscape and contributing to the rock cycle.