Sourceforge is one of those very rare venues that can fairly be described as unique. It is the primary and in some cases sole venue for the developers of 'open source' software to develop and distribute their wares, and it is one of the longest-established web services. It is owned and operated by the same company that owns Slashdot and Think Geek, which for most web aficionados is about as good a reference as it gets.
For anyone who didn't follow any of that, a brief explanation. The term 'open source' refers to the 'source code' that makes up a computer program, or application; not the part you see, or play with, but the coding, usually in arcane and exotic programming languages, that makes everything happen. Anyone who saw The Matrix at the movies will be with me, immediately.
This code is, in most cases, protected by God-knows-how-many licenses and copyrights and intellectual rights, so as to (a) protect the program writer's personal and corporate copyrights, and (b) maximize the profits that can be made from selling the finished product.
In reality, (b) generally comes before (a). In any event, this sort of code is 'closed', and may not be copied, modified or redistributed.
In the case of many software products today, they never even belong to you, the person who bought them, at all. They are licensed from the owners, so that you only have permission to use them, and not to copy or distribute them or even trade them or give them away. As you'll probably already know, you are not even allowed to make a backup copy for your own personal use, any more. Such is the corporate paranoia about illegal copying and redistribution.
Now for the alternative, the open source model. There are ten basic rules, which I have paraphrased here. I apologize in advance for any inaccuracies, this is intended to give readers a broad idea of what open source is about, rather than to be definitive.
1. Free redistribution: You may take an application and include it in a compilation of applications, free of charge and any royalties or commissions.
2. With only a very minor limitation, you are obliged to redistribute the source code along with every copy of the finished application, so that other programmers and developers may also read and modify and redistribute it, exactly as you did.
3. You may derive a new application, or make modifications to the current one, and these must also be distributed under the same terms as the original.
4. If the original author wants to protect his or her code, anyone developing the application further must respect this, and provide their own 'patch' files to modify the application when it is re-created or 'built' into a version that is ready for use. In other words, the basic 'engine' must remain intact if the author wishes, and extras must remain additional, with no modifications being made to that original code.
5. The license must not discriminate against anyone.
6. The license must not discriminate against use. If an application may be used either to design a system for world peace or a system for world destruction, it must be distributed with the rights to do either or both. No moral, economic or other kinds of judgment are allowed.
7. The license follows all copies of the application and is complete and binding on everyone, as it is; no additional licenses are ever required.
8. If an application is included in a distribution which includes several applications, and then later on, that single application is extracted and once again used or distributed alone, there must be no changes to the original license terms.
9. There must be no limitations set on other software by a piece of open source software. If an open source application of yours is used by someone else in a compilation that includes commercial for-profit applications, you must accept that. You can't demand that they only use further open source applications, only.
10. The license is free of any limitations or advantages that might be gained by using this or that kind of computer, or this or that kind of cell phone or PDA or any type of technology whatsoever. You may develop an app that only runs in Windows, but the license must not require that versions of the app distributed under that license may only ever run in Windows.
It is and always has been a characteristic of the internet that people want to create and distribute for free. There are thousands, maybe hundreds of thousands, of creators out there who don't follow the commercial model and, against the assumptions we usually make about the reasons people create, want to give away the fruits of their labors for nothing. I am writing this in the Firefox browser, a free application. I use the VLC player for my movies, another free application. I have free applications for listening to music, for office work, for just about anything I need to do on a computer. This has only been possible since the advent of the web, which provides everyone with the opportunity to create and distribute and download for free. As soon as it was no longer necessary to go to a store and pay money for everything, creators were giving away their work.
At the other end of the scale, of course, big corporations have continued to market their wares for money and even increased the charges for their licensed products. Without wishing to pick on anyone in particular but just as an example, a product like the Adobe CS5 Creative Suite of programs is so expensive as to be hopelessly beyond the resources of almost every individual and tough for even small businesses to justify. Yet, some will argue, it is no more than a software download, no different from a free, open source application of similar size. This is the philosophy that has created Open Office, a free competitor for Microsoft Office; it drives the development of the Linux operating system, a direct and improving competitor to Microsoft Windows and other commercial systems, and it continues to fuel the development of free alternatives to many of the expensive commercial applications out there.
Back to Sourceforge, then, and to wind up, this is where hundreds of free, open source applications may be found. Just about anyone writing open source apps is going to use Sourceforge either directly or indirectly. Many projects have their own websites (for example, www.videolan.com for the open source media player that everyone 'in the know' uses), but still store their work at Sourceforge and direct their users to that site for downloads. In this way, they save stress on their own servers. Others may not have their own sites and use Sourceforge directly, so that their followers just go straight there for their downloads. Many, many developers have products in development that aren't necessarily ready for the polish of a final version but which people still want to use, or test out, in their development stages. These may often be found at this site. Teams of developers themselves may use the site to access builds of their products.
To be frank, most of the above is waffle, because I'm sitting here in McDonald's over a refill coffee and waiting for my laptop to charge up. I could have summed it up simply by quoting the Sourceforge site's own definition:
"We provide free services that help people build cool stuff and share it with a global audience."
I am still promising myself to learn how to write concisely. One day.