Answer:
A summary of what a rock is.
Step-by-step explanation:
Simpler terms: A rock is a substance made up of solid crystals of different types of minerals that fused together to make what we know as rocks. They are formed naturally.
Slightly more complex but shorter terms: A rock is an aggregate of one or more minerals. They are formed naturally.
There are three types of rocks which are: igneous, metamorphic, and sedimentary.
Igneous rocks are formed from molten material.
Metamorphic rocks form from alterations(environmental changes and the subtraction/addition of chemical components) other types of rocks, including metamorphic rocks themselves. (This one may not be spot on, I haven't studied this type as much.)
Sedimentary rocks are formed from deposited and lithified mineral material. Fossils are often found in this type of rock.