How many main types of rocks are categorized in geology?

In geology, rocks are classified into three main types based on their formation processes: igneous, sedimentary, and metamorphic.

Igneous rocks form from the solidification of molten material, either from volcanic eruptions or from cooled magma beneath the Earth’s surface. Sedimentary rocks are created from the accumulation and compression of mineral and organic particles, often found in layers, while metamorphic rocks arise from the transformation of existing rock types due to heat, pressure, or chemically active fluids.

This classification system is foundational in geology, helping scientists understand the Earth's processes and the history of its materials. Each rock type has distinct characteristics and is formed through different geological processes, which is why there are specifically three main categories recognized in the field.