Software
Free Software
"Free software" is a matter of liberty, not price. To understand the concept, you should think of "free" as in "free speech," not as in "free beer." Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. --Richard Stallman [...]Open Content [...]
Open content, coined by analogy with open source, describes any kind of creative work (for example, articles, pictures, audio, video, etc.) that is published under a non-restrictive copyright license and format that explicitly allows the copying of the information. (An example is the GNU Free Documentation License, which is used by Wikipedia and Nupedia.) "Open content" is also sometimes used to describe content that can be modified by anyone. Of course, this is not without prior review by other participating parties--but there is no closed group like a commercial encyclopedia publisher which is responsible for all the editing.
Just as open source software is sometimes described simply as Free Software (not to be confused with Freeware), open content materials can be more briefly described as free materials. But not every open content is free in the GNU GPL sense (for instance the Open Directory). --http://www.wikipedia.org/wiki/Open_content, Aug 2003
Killer application
A killer application (commonly shortened to killer app) is a computer program that is so useful that people will buy a particular brand of computer simply to run that program.
The first example of a killer app is generally agreed to be the VisiCalc spreadsheet on the Apple II platform. The machine was purchased in the thousands by finance workers (in particular, bond traders).
The next example is another spreadsheet, Lotus 1-2-3. Sales of IBM's PC had been slow until 1-2-3 was released, but only months later it was the best selling computer.
A killer app can provide an important niche market for a non-mainstream platform. Aldus PageMaker and Adobe PostScript gave the graphic design and desktop publishing niche to the Apple Macintosh in the late 1980s, a niche it retains to this day despite PCs running Windows having been capable of running versions of the same applications since the early 1990s.
There have been a number of new uses of the term. For instance the Mosaic web browser is generally credited with starting the rush of computer users to join the Internet by showing them the World Wide Web, although others argue that e-mail was the reason. This does not hold up to scrutiny, as email preceded the internet. --http://en.wikipedia.org/wiki/Killer_app [Jun 2004]