I wouldn’t expect anyone that isn’t familiar with linux, to even understand what the open source package called wine is, but basically the long and short of it is that it’s a way to run windows applications without having Windows itself.
The open source version can run some things, and the commercial version usually can handle a lot more applications because of certain tweaks they implement. From games to pretty advanced applications on MacOSX and Linux.
In any case, apparently due to some goals set by the CEO that were met, they’ve decided that today there will be free licenses for everyone! (one license per user).
So if you don’t have a copy of this, or you’re just looking for something to run applications and you don’t own Parallels or the like or just want to try it out, go and get yourself a copy and a serial. Having used Codeweavers and Transgaming versions of wine in the past, I can say that you can only be surprised how many things are supported without having actual Windows around.