Intrusions refer to the act of entering a space or situation where one is not welcome or authorized. This can occur in various contexts, such as in nature, where an animal might intrude into another's territory, or in cybersecurity, where a hacker gains unauthorized access to a computer system. In geology, intrusions can also describe the movement of molten rock, known as magma, into existing rock formations. This process can create new geological features and is a key aspect of the Earth's dynamic crust. Understanding intrusions helps in studying both ecological and geological systems.