What is a rock cycle?

Have you had a look at the Bitesize article http://www.bbc.co.uk/schools/ks3bitesize/science/environment_earth_universe/rock_cycle/revise1.shtml if you are still confused, tell us where you need help

A rock cycle is a cycle in which rocks are created and have been going through the rock cycle for millions of years. The rock cycle is whena volcano erupts the magma cools down to create an igneous rock then it weathers over time and goes back to magma this rock cycle can take over millions of years. As magma cools down it creates a new rock and crystals some crystals are small due to the time it took for the magma to cool if the magma cools quickly it will have small crystals. Seing as magma is very hot it mostly cools down underground this takes more time because in the mantle it is very hot meaning it will cool down slower, as on the earths crust it cools fast meaning it has tiny crystals.