Here's a breakdown:

* Magma: Molten rock found beneath the Earth's surface.

* Intrusion: The process where magma forces its way into pre-existing rock, causing it to cool and solidify.

The resulting solidified magma is called an igneous intrusion or pluton. There are various types of intrusions based on their shape and size, such as:

* Batholith: Large, irregular-shaped intrusions.

* Stock: Smaller, irregular-shaped intrusions.

* Sill: Tabular intrusions that are parallel to the surrounding rock layers.

* Dike: Tabular intrusions that cut across the surrounding rock layers.

Intrusions play a significant role in the formation of mountains, and can also create mineral deposits.