Internal is an adjective that means existing or situated within the limits or surface of something.
In different contexts, internal can refer to:
1. Internal organs - the organs inside the body
2. Internal affairs - matters concerning a country's domestic policies
3. Internal memory - the built-in storage of a computer or device
4. Internal combustion engine - an engine that generates power by burning fuel inside
5. Internal medicine - the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases