That Wine took fifteen years to reach version 1.0 reveals the difficulties of getting Windows applications to run in Linux. With Wine, it is possible to install certain Windows programs in Linux, without running a virtual machine. While not a perfect science, WINE does a pretty good job and some of the programs on the platinum list are actually quite new.
Wine works by implementing Windows APIs in Linux. The following explanation gives a good basic understanding of the concept:
When an application tries to make a Windows system call, the Wine libraries intercept it and perform whatever action was requested– only they do it the Linux way, instead of the Windows way. The result is that the applications do what you expect them to do, even though they aren’t running on Windows.
So what works and what doesn’t? The application database divides the programs based upon how well they install and run. The newest programs tend to be a little problematic, but there are some fairly recent editions amongst the platinum ranks, including Photoshop CS2 and Dreamweaver 8. Microsoft Word ’03 gets a gold rating due to some minor bugs. [WINE, Yahoo! News]