How does the IDisposable pattern and the 'using' statement help manage UNMANAGED resources that the garbage collector doesn't automatically clean up?

The garbage collector only manages MANAGED memory — it doesn't know how to release unmanaged resources like file handles, database connections, or OS handles. IDisposable's Dispose() method provides a deterministic way to release those resources explicitly, and 'using' guarantees Dispose() is called automatically when the object goes out of scope, even if an exception occurs.

public class FileWrapper : IDisposable {
  private readonly FileStream _stream;
  public FileWrapper(string path) { _stream = File.OpenRead(path); }
  public void Dispose() => _stream.Dispose(); // releases the unmanaged file handle
}
using (var wrapper = new FileWrapper("data.txt")) { /* ... */ } // Dispose() guaranteed to run