Free and/or Open Software is actually a very broad category, that many people have an interest in. This page is designed to go over the types of programs that are described (note: this is more about legal issues than the programs themselves any program can fall in one ore more of these categories). Here is a quick list of the types:
- Free as in Free Speech
- Free as in Free Beer
- Open Source (Open Source Initiative)
- Open Source (Literal)
What's The Big Deal?Edit
“Open source is a development methodology; free software is a social movement.”  These are distinct but similar groups, with a few things in common. One of the more interesting ones is bad names (we will list the "official version" first and have the second after it).
Free as in Free SpeechEdit
The "Official Definition" can be found here. However, just a summery it is in regards to the liberties of the end user. Which include the right to
- The freedom to run the program, for any purpose (freedom 0).
- The freedom to study how the program works, and change it to make it do what you wish (freedom 1). Access to the source code is a precondition for this.
- The freedom to redistribute copies so you can help your neighbor (freedom 2).
- The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.
All four of these are from here 
Free as Free BeerEdit
This is the problem meaning for "free software" one of the meanings for free (and the most common one) is in regards to money.
Open Source (Open Source Initiative)Edit
The "Official Definition" can be found here.
Open Source (Literal)Edit
You can view the source code.