Let's start this with a use case. Suppose you have a client, owning an insurance company, consisting of several more or less independent departments. Let's say car insurance, life insurance, health insurance and so on. Now, that client needs a website for his intranet, so employees can efficiently communicate with each other. One important aspect of office communication is collaboration in teams. For example, the life insurance team should be able to work out a plan for a new life insurance policy without the health insurance people snooping around in their work.