Open Software:

With three major operating systems and a growing number of web and mobile based solutions, finding the right application for your task can be a daunting challenge. Often it seems worth the fee to purchase proprietary software. In some cases this may be the right solution. Increasingly, there are free solutions, but they are still proprietary in nature. Many web based applications are a good example of this.

Closed systems are dangerous for the simple fact that they are closed. If the company goes out of business, the information you've created with that system may be locked up with that system and difficult to migrate to a new system. This is called vendor lock in. In the case of web applications, that information could simply disappear if the company disappears. More often than not, you'll want access to the data you've spent your time creating. With an open system, you have some assurance that no matter what happens, there is a path to accessing your information.

http://www.fsf.org/ http://tazebao.dyne.org/privacy/

https://plus.google.com/u/0/113210431006401244170/posts/Uz2mWZZ5rqY

(pay for commercial services when you need them)

Licenses:

There are many licenses that software is distributed under. Some of the defining features are:

-Closed Source

-Open Source
-Copyleft -MIT/BSD

These are explained more thoroughly here: