What is the term for magma that reaches the Earth's surface?

Lava is the term used to describe magma that has erupted onto the Earth's surface. When magma is underground, it is still in a molten state but is contained within the Earth. Once it breaks through the surface through a volcanic eruption, it is referred to as lava. This transition indicates that the substance is now exposed to the atmosphere and can flow, solidify, and contribute to various geological formations such as lava flows and volcanic rocks.

Understanding this distinction is essential in geology, as the properties and behavior of magma beneath the surface can differ significantly from lava, which can vary in temperature, composition, and physical characteristics as it interacts with the atmosphere and the environment.