This page should collect some ideas in connection with collaborative editing.
Collaborative editing means that two or more persons edit the same document at the same time, but possibly at different locations.
Therefore their editing actions must be shared over a network, which will be most naturally the internet. The different editors therefore need some piece of software which supports this way of editing and keeps the shared document in a defined state.
The different editors can work on different parts of the document. The software must solve editing conflicts in an intuitive way.
SubPathetaEditLinks has many useful links to similar projects.