What do we mean by "open source?" Depending on how closely you monitor the tech world, you may have never even heard the term. Open source refers to software with a license that gives users the freedom to run the software for any purpose, to study and modify the software, and to redistribute copies of either the original or modified program (without having to pay royalties to previous developers).

What open source is
Prior to 1998, most open source projects were produced under one of four licenses, the most popular of which is the GPL (GNU General Public License). The criteria for software to be considered under this license include:

• Free redistribution - No need worrying about copying the software from your desktop to your laptop or from an old coputer to your new one.
• Access to source code - No secrets here. This may only be a curiosity without the next item, though.
• Allow derived works - This is powerful when combined with access to the source code. If the software doesn't quite meet your needs...no problem. Just change it.  

The full list of GPL (and other open source license language) is available here.

What open source is not
Open source doesn't necessarily mean "free." As stated in the language of the GPL, "When we speak of free software, we are referring to freedom, not price." While most open source products are free, open source is not about getting something for nothing. If the CMS (Content Management System) you just installed works beautifully, but doesn't handle news stories like you want, unless you're a programmer, you will have to pay for it to be modified. There are also open source projects that are strictly for fee, such as some of the Linux distributions. Software is, after all, still a business.

Popular open source projects

By reading these words, you're taking advantage of at least four open source products. This site is being delivered by the Apache server running on a Linux operating system. The site itself uses the Joomla CMS, which stores content in a MySQL database. You may even be viewing it with a Firefox browser (if not, I highly recommend it). Check out this list of available open source projects.

Open source vs proprietary

Open source doesn't necessarily mean better or cheaper, but often does. Author David Wheeler found that in many cases, open source products are "...equal to or superior to their proprietary competition." ( Read his findings here. )

Ultimately, the decision of using open source products or proprietary software depends on your specific needs and circumstances. But with a thriving development community continually creating new and better tools, and a growing number of business users switching to open source solutions, the open source movement is nearly impossible to ignore. Proprietary software companies are taking notice. Ultimately, that's good for everyone.