Complex sentence: Ensemble collaboration is a large-scale online collaboration (mass Internet collaboration) where members come together for a specific purpose and then disband; he connections still remain in case a new group needs to be formed.
Split into simpler sentences: Ensemble collaboration is a term used to describe large-scale online collaboration (mass Internet collaboration) where members come together ('ensemble') for a specific purpose and then disband. However the connections remain in case a new group needs to be formed.