Describe snapshots and how they can be useful when using virtual machines?

What will be an ideal response?

Snapshots provide a fast and easy way to return or "revert" the virtual machine to a previous state, which is particularly useful in a development environment. After taking a snapshot, you could make a change to a program and test the change. If the change did not work as intended, you could revert the virtual machine to the previous state and try a different program change.