Software categories are groups ofsoftware. They allow software to be understood in terms of those categories, instead of the particularities of each package. Different classification schemes consider different aspects of software.
Computer software can be put into categories based on common function, type, or field of use. There are three broad classifications:
TheGNU Project categorizes software bycopyright status:free software,open source software,public domain software,copylefted software, noncopylefted free software, lax permissive licensed software,GPL-covered software, theGNU operating system, GNU programs, GNU software,FSF-copyrighted GNU software, nonfree software,proprietary software,freeware,shareware, private software andcommercial software.[1]
Free software is software that comes with permission for anyone to use,copy anddistribute, either verbatim or with modifications, either gratis or for a fee. In particular, this means thatsource code must be available. "If it's not the source, it's not software." If a program is free, then it can potentially be included in a free operating system such as GNU, or freeversions of theLinux system.
Free software in the sense of copyright license (and the GNU project) is a matter of freedom, not price. However proprietary software companies typically use the term "free software" to refer to price. Sometimes this means a binary copy can be obtained at no charge; sometimes this means a copy is bundled with a computer for sale at no additional charge.[1]
Open-source software is software with itssource code made available under a certainlicense to its licensees. It can be used and disseminated at any point, the source code is open and can be modified as required. The one condition with this type of software is that when changes are made users should make these changes known to others. One of the key characteristics of open source software is that it is the sharedintellectual property of all developers and users. TheLinux operating system is one of the best-known examples of a collection of open-source software.[2]
Copylefted software is free software whose distribution terms ensure that all copies of all versions carry more or less the same distribution terms. This means, for instance, thatcopyleft licenses generally disallow others to add additionalrequirements to the software (though a limited set of safe added requirements can be allowed) and require making source code available. This shields the program, and its modified versions, from some of the common ways of making a program proprietary. Some copyleft licenses block other means of turning software proprietary.
Copyleft is a general concept. Copylefting an actual program requires a specific set of distribution terms. Different copyleft licenses are usually "incompatible" due to varying terms, which makes it illegal to merge the code using one license with the code using the other license. If two pieces of software use the same license, they are generally mergeable.[1]
Noncopylefted free software comes from the author with permission to redistribute modify and add license restrictions.
If a program is free but not copylefted, then some copies or modified versions may not be free. A software company cancompile the program, with or without modifications, and distribute theexecutable file as a proprietary software product. TheX Window System illustrates this approach. TheX Consortium releasesX11 with distribution terms that make it non-copylefted free software. If you wish, you can get a copy that has those distribution terms and is free, however nonfree versions are available. There areworkstations and PCgraphics boards for which nonfree versions are the only versions that will work. The developers of X11 made X11 nonfree for a while; they were able to do this because others had contributed their code under the same non-copyleft license.[1]
Shareware is software that comes with permission to redistribute copies but says that anyone who continues to use a copy is required to pay. Shareware is not free software or even semi-free. For most shareware, source code is not available; thus, the program cannot be modified. Shareware does not come with permission to make a copy and install it without paying a license fee, including fornonprofit activity.[1]
Like shareware, freeware is software available for download and distribution without any initial payment. Freeware never has an associated fee. Things like minor program updates and smallgames are commonly distributed as freeware. Though freeware is cost-free, it iscopyrighted, so other people can not market the software as their own.[3]
This classification has seven major elements. They are:platform andmanagement,education andreference, home and entertainment, content andcommunication, operations and professional, product manufacturing and service delivery, andline of business.
