Wine is a free software application that aims to allow computer programs written for Microsoft Windows to run on Unix-like operating systems. Wine also provides a software library, known as Winelib, against which developers can compile Windows applications to help port them to Unix-like systems.
Wine is not a full emulator, but is instead a compatibility layer, providing alternative implementations of the DLLs that Windows programs call, and a process to substitute for the Windows NT kernel. Wine is predominantly written using clean-room reverse-engineering, to avoid copyright issues.
The project lead is Alexandre Julliard.
The name Wine derives from the recursive acronym Wine Is Not an Emulator. While the name sometimes appears in the forms WINE and wine, the project developers have agreed to standardize on the form Wine
Architecture
Wine implements the Windows API entirely in user space, rather than as a kernel module. Services normally provided by the kernel in Windows are provided by a daemon known as the wineserver. The wineserver implements basic Windows functionality, as well as integration with the X Window System, and translation of signals into native Windows exceptions.
Although Wine implements some aspects of the Windows kernel, it is not possible to use native Windows drivers with it, due to Wine's underlying architecture. This prevents certain applications from working, such as some copy-protected titles.
Portability
Wine is primarily developed for Linux, but the Mac OS X, FreeBSD and Solaris ports are currently well-maintained.Wine is also available for OpenBSD and NetBSD through OpenBSD Ports and NetBSD pkgsrc respectively. Outdated versions of Wine's DLLs are available for Microsoft Windows, but Wine does not fully compile or run on Windows yet.
Corporate sponsorship
The main corporate sponsor of Wine is CodeWeavers, which employs Julliard and many other Wine developers to work on Wine and on CrossOver, CodeWeavers' supported version of Wine. Crossover includes some application-specific tweaks not considered suitable for the WineHQ version, as well as some additional proprietary components.
The involvement of Corel for a time assisted the project, chiefly by employing Julliard and others to work on it. Corel had an interest in porting WordPerfect Office, its office suite, to Linux (especially Corel Linux). Corel later cancelled all Linux-related projects after Microsoft made major investments in Corel, stopping their Wine effort.
Other corporate sponsors include Google, which hired CodeWeavers to fix Wine so Picasa ran well enough to be ported directly to Linux using the same binary as on Windows; Google later paid for improvements to Wine's support for Adobe Photoshop CS2. Wine is also a regular beneficiary of Google's Summer of Code program.
