Demos Demos are free, and typically include a subset of features of a commercial program. While shareware is often developed by individuals, demos are typically of applications developed by the big software companies. The less interesting demos are not interactive, that is they show screens and list features of different parts of a program. This kind of demonstration is being done more and more online, at a company's Internet site. They can be useful in determining whether or not to buy.
Interactive demos are much more interesting.
They include a subset of the functionality of the full program, but that subset can be substantial, and give a very good idea of what the application is like. If a company is confident about its product, a demo can give people a taste for it and stimulate sales. There are some wonderful Demos available for download. Some companies are providing their demos as online games, which serves the same purpose. However, this limits access by families that do not have fast modems.