Petri Kuittinen's essay on all things underground demo.<p></p><em>Computer demos should not be confused with the demo versions of commercial programs. They are "demos" too, but the word "demo" in this text means a program whose purpose is to present the technical and artistic skills of its makers and produce audiovisual pleasure to the viewer. A computer demo usually includes various kind of real-time produced computer graphics effects which have little relation to each other accompanied by music. In a way a demo could be described as a sort of music video or a short computer animation film without a plot or message other than just "hey, I can do this" and "greetings to my friends". Of course there is exception to every rule and some demos have a plot and message.</em>