Wine stands for WINE is NOT an Emulator. WINE is a compatibility layer.
Since it isn't an emulator it should not be called one. Also Wine is not
virtual Windows. It is a Windows compatibility layer which includes enough
Windows APIs and libraries to run many, but not all Windows programmes in
Linux (or Mac).

WINE has a registry and a dummy Windows file system. Since it is NOT an
emulator many Windows programmes run faster in Wine than Windows because
Linux uses less overhead than Windows. Wine uses "bottles" where each
programme is isolated and managed. You can have a Windows XP bottle and a
Windows 200 bottle, etc. You can have more than one of each. To ensure
greater compatibility you should set the default to Windows XP. I think that
Windows 2000 is the default, but that may have changed in recent releases.