Basically, it is like the Inception movie with computers. You have emulated software computers called Virtual Machines running on a physical computer. And you can even have Virtual Machines running within Virtual machines if you want to (but this will require a more powerful laptop in some cases).
Each Virtual Machine is a sandbox. Remember the reasons for using them are to prevent the following risks:
- Mitigate local data leaks and easier clean-up in case of risk (everything is contained within the VM and only the VM identifiers could be leaked and not the Host Hardware identifiers)
- Reduce malware/exploit attack surfaces (if your VM is compromised, the adversary still must figure out he is in a VM and then gain access to the Host OS which is not so trivial).
- Mitigate online data leaks by being able to enforce strict network rules on Virtual Machines for accessing the network (such as passing through the Tor Network).
Source: The Hitchhiker’s Guide to Online Anonymity, written by AnonyPla © CC BY-NC 4.0