Here's a breakdown:

* Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by intense heat and pressure. This process doesn't melt the rock completely, but it changes its mineral composition, texture, and sometimes even chemical makeup.

* Heat can come from the Earth's interior, from magma intrusions, or from friction due to tectonic plate movement.

* Pressure can come from the weight of overlying rock layers, from tectonic plate collisions, or from the pressure of fluids within the rock.

Some common examples of metamorphic rocks include:

* Marble: Formed from limestone

* Slate: Formed from shale

* Quartzite: Formed from sandstone

* Gneiss: A banded metamorphic rock formed from various igneous or sedimentary rocks

Let me know if you'd like to learn more about any specific metamorphic rock!