Why Wine is so important
A lot of people in popular discussion forums keep thinking that Wine is "the last thing that Linux needs" or that it is "not important".
We are listing some info here that is supposed to thoroughly defeat these and other claims.
Five key points:
* Supply diversification
* Large homogeneous populations are a risk to society
* Any Windows replacement must run Windows applications
* Chicken-and-egg problem for Linux on the desktop
* Wine benefits
Diversifying your supply is universally considered to be an important aspect of risk management.
Yet, The US Department of Justice has "found" that Microsoft Windows is run by more than 95% of personal computers. Even taking Apple's Mac OS into account, Microsoft Windows is still present on more than 80% of computers, and this is likely also true in most other countries, not just in the US. Thus governments, companies and home users all over the world ultimately depend on a single provider: Microsoft.
The question is not whether Microsoft has evil intents, or whether it may go out of business, but whether its plans match yours. A company may want to deploy thin clients to simplify administration and save money on per-client Windows licenses. But is Microsoft going to make it viable and undercut its Windows market? Where is the alternative if Microsoft implements its software subscription model? If Microsoft is not interested in catering to your market, then you have no other provider to turn to.
Large homogeneous populations are a risk to society
Another aspect is that such large homogeneous populations are dangerous to society. The irish learnt this the hard way when their potato crop was destroyed by a fungus, causing the 1845 "Potato Famine" and killing more than a million people (about 10% of the population). In a large homogeneous population, all individuals share the same vulnerabilities. Find one vulnerability and you can annihilate the whole population. Since then, we, as a society, have learnt our lesson. Or have we?
As mentioned above, Microsoft Windows is run on an overwhelming proportion of personal computers. Even taking into account the variations between different versions of Windows, mostly between Windows 9x and the Windows NT family, this represents a large homogeneous population. One on which most governments, most businesses, and many households depend on.
The elements of this population, like all other complex systems, are not miraculously exempt from vulnerabilities. The Code Red epidemic of the summer of 2001 is there to remind us of that. Code Red did what any "virus" presented with a large homogeneous population would do: it infected more than 359.000 computers in just the first day. Fortunately, it infected a less common member of the Windows family and was quite harmless: it did not randomly corrupt files or format your hard-drive. , 
It is only a matter of time before a more virulent worm appears. The only way to decrease its impact is to diversify the OS population. This issue is now considered serious enough that security analysts are calling our reliance on Microsoft Windows a threat to national security.
Because it is an alternate implementation of the Win32 API and runs on top of a completely different OS, Wine does not have the same flaws and thus can provide this needed diversity.
Any Windows replacement must run Windows applications
The dependency is not so much on Microsoft Windows as it is on Windows applications. Boxed off-the-shelf applications, games, in-house applications, vertical market applications, are what prevents users, companies and governments from switching to another operating system. Even if 90% of the needs of most users are taken care of if you can provide them with an office suite, an email client, a browser, and a media player, then there will still be a remaining 10% of their needs, potentially critical needs, that are not met. Unfortunately these remaining 10% are spread across a wide spectrum of applications: thousands of applications running the gamut from games to specialized accounting software for French farms, via Italian encyclopedias, German tax software, child education software, banking software, in-house software representing years of development, etc. It is the availability of all this software that makes Windows so compelling and its monopoly so strong. No platform will become mainstream unless it runs a significant portion of that software and lets individuals, companies and governments preserve their investments in that software.
Chicken-and-egg problem for Linux on the desktop
This brings us to the chicken and egg issue of Linux on the desktop. Until Linux can provide equivalents for the above applications, its marketshare on the desktop will stagnate. But until the marketshare of Linux on the desktop rises, no vendor will develop applications for Linux. How does one break this vicious circle?
Again, Wine can provide an answer. By letting users reuse the Windows applications they have invested time and money in, Wine dramatically lowers the barrier that prevents users from switching to Linux. This then makes it possible for Linux to take off on the desktop, which increases its market share in that segment. In turn, this makes it viable for companies to produce Linux versions of their applications, and for new products to come out just for the Linux market.
This reasoning could be dismissed easily if Wine was only capable of running Solitaire. However now it can run Microsoft Office, multi-media applications such as QuickTime and Windows Media Player, and even games such as Max Payne or The SIMS.
Almost any other complex application can be made to run well given a bit of time. And each time that work is done to add one application to this list, many other applications benefit from this work and become usable too.
Have a look at our Application Database to get an idea on what can be run under Wine.
Last but not least, Wine can provide benefits over Windows right now:
* 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.
* Unix has always made it possible to write powerful scripts. Wine makes it possible to call Windows applications from scripts that can also leverage the Unix environment to its full extent.
* Wine makes it possible to access Windows applications remotely, even if they are a few thousand miles away.
* Wine makes it economical to use thin clients: simply install Wine on a Linux server, and voila, you can access these Windows applications from any X terminal.
* Wine can also be used to make existing Windows applications available on the Web by using VNC and its Java client.
* Wine is Open Source Software, so you can extend it to suit your needs or have one of many companies do it for you.