Online collaboration at a minimum involves more than one person collaborating via the Internet, but people typically use the phrase to mean something much more specific. The contributors to most online collaborations are typically self-selecting, in principle unlimited in number, and with few exceptions,[1] require no special credentials for participation. Moreover, the collaboration itself is considerably different from traditional sorts of collaboration, in which different people were assigned different parts of a jointly-written work, or in which people literally worked side-by-side. By contrast, online collaborators usually work without any significant guidance "from above" (see top-down vs. bottom-up), other than the statement of the rules of the game, so to speak; and work can be done concurrently from wherever the Internet extends. In short, the contributors to an online collaboration act as largely independent agents, with a collaborative technology--e.g., a wiki--defining ways in which such independent agents can work together.
An interesting and legitimate question can be raised whether rating websites, such as digg.com, or aggregation of content, such as Google Earth does, should be called collaborative. Sometimes such websites are thrown in with Wikipedia, for example, as being collaborative. We can make some sense of this: the product as experienced by the end-user is a single, albeit highly diverse, thing, and many people contribute bits of pieces to create that product. But sometimes "collaborative" seems to be applied more strictly just to wikis, open source software, and other Internet projects in which people can directly edit or develop the precise content (or code) that others have contributed.