How Is Public Domain Software Different From Open Source?
Open source software allows users to access and alter the source code of the program itself. The source code is basically a list of commands that dictate how the program executes. Some open source applications have restrictions on their use and distribution, but many do not.
Is There a Difference Between Open Source Applications and Public Domain?
Open source applications are not under public domain, and this allows people to freely use their works. Public domain software typically does not allow access to source codes, although this is not always the case. Open source software does have copyrights.
Sometimes the term "open source" is used interchangeably with "public domain" software, but they're not the same thing.
The Determining Factors Are Copyrights or Use Restrictions
The key distinction between OS and public domain software is not whether the source code is accessible, but whether there are any licensing requirements or other restrictions on using the program, altering the source code, redistributing the program or on the copyright. If there are, it is open source, not public domain software.
Open Source Initiative, a 501(c)(3) California-based nonprofit, offers a very detailed and legal definition of open source software, who can use it, and how. They also have a great alphabetical listing of companies that offer open source software if you wish to investigate a particular company. OpenSource.org is a great place to find out more about how you can develop, collaborate and use OS software.
Other Important Distinctions
OS software can be freely shared, used, and even changed by anyone. It's developed through the contributions of many and distributed under licenses that must comply with certain criteria for use. The license cannot discriminate against anyone. In other words, you cannot bar certain groups of people from using the software. It must allow for derived works.
Open source software comes in all shapes and sizes and can serve multiple purposes. Examples include LINUX, Apache, Firefox, KOffice, Thunderbird, OpenOffice, KOffice, and SquirrelMail. Firefox is a simple web browser, whereas LINUX is more complicated. It's a UNIX-based operating system. OpenOffice is an office suite offered by Apache.
In the case of OpenOffice, you can download and install the program on pretty much any computer – for free, even if you install it on multiple computers. Make copies and hand them out to friends and family. There are no license fees. Use it as you would any other word processing, spreadsheet or database program. And if you have a problem – such as that a bug pops up – or if you think you can make it better, you can report it or just tweak the issue yourself. The program allows users to "enhance" it, according to Apache.
Is It Safe?
Anytime you allow access by multiple users, the issue of viruses arises. Proceed with caution and make sure you have a good anti-virus application in place when you access open source software.