Wine is often used as a recursive acronym, standing for "Wine Is Not an Emulator". Sometimes it is also known to be used for "Windows Emulator"
(An emulator duplicates (provides an emulation of) the functions of one system using a different system, so that the second system behaves like (and appears to be) the first system.). In a way, both meanings are correct, only seen from different perspectives. The first meaning says that Wine is not a virtual machine, it does not emulate a CPU, and you are not supposed to install Windows nor any Windows device drivers on top of it; rather, Wine is an implementation of the Windows API, and can be used as a library to port Windows applications to UNIX. The second meaning, obviously, is that to Windows binaries (.exe files), Wine does look like Windows, and emulates its behaviour and quirks rather closely.
Throughout the course of its development, Wine has continually grown in the features it carries and the programs it can run. A partial list of these features follows:
Support for running Win32 (Win 95/98, NT/2000/XP), Win16 (Win 3.1) and DOS programs.
Optional use of external vendor DLL files (such as those included with Windows).
X11-based graphics display, allowing remote display to any X terminal, as well as a text mode console.
Desktop-in-a-box or mixable windows.
DirectX support for games.
Modem, serial device support.
ASPI interface (SCSI) support for scanners, CD writers, and other devices.
Advanced unicode and foreign language support
Wine is an open source project, and there are accordingly many different versions of Wine for you to choose from. The standard version of Wine comes in intermittent releases (roughly twice a month), and can be downloaded over the internet in both prepackaged binary form and ready to compile source code form. Alternatively, we can install a development version of Wine by using the latest available source code from the Git repository
Wine makes it possible to take advantage of all the UNIX strong points (stability, flexibility, remote administration) while still using the Windows applications you depend on