Scientists classify rocks into three main categories based on how they are formed. The three categories are:

* Igneous rocks: Formed from the cooling and solidification of magma (molten rock) or lava.

* Sedimentary rocks: Formed from the accumulation and cementation of sediments, like sand, mud, or shells.

* Metamorphic rocks: Formed when existing rocks (igneous, sedimentary, or other metamorphic rocks) are transformed by heat, pressure, or chemical reactions.