"The basic idea behind open source is very simple: When programmers can read, redistribute, and modify the source code for a piece of software, the Software evolves. People improve it, people adapt it, people fix bugs. And this can happen at a speed that, if one is used to the slow pace of conventional software development, seems astonishing." (opensource.org in Bruns 2008).
This practice differs significantly to the somewhat traditional idea of "closed source software" where the source code remains confidential. Such closed source software examples include Windows, Office and Internet Explorer. These programs are developed by paid staff teams of a company and therefore are subject to hierarchical directions and restrictions. This more traditional idea of closed source software runs various parallels to the characteristics describing offline communities. This sort of software development is based on a business model and perhaps one of it's main objectives is to sell the software and make a profit. By doing this, obviously they are going to strive to produce something that is responsive to user needs in order to sell more, but perhaps they may not be quite so focused on, or have as much of an idea of, what exactly it is that the user needs compared with a group of community users that create open source software.
References:
Feller, J., B. Fitzgerald, S. Hissam and K. Lakhani. (2005). Perspectives on Free and Open Source Software. Retrieved May 10, 2008, from http://mitpress.mit.edu/books/chapters/0262562278.pdf