Snapshot will make a copy of your disk, saving it away for future experiments based on the same profile. This is a complete disk copy, everything is saved. The next user to instantiate this profile will use this new disk image.

If your profile is already using a disk image created via snapshot (or Clone), the original disk image is saved for you. Note that only one copy of the image is saved.

After you click to confirm, the node in your experiment will be shutdown, and a disk image captured. You will be able to track the progress of the image capture as it proceeds. When it is done, the "Ready" flag will be checked, and your node rebooted.

Clone vs. Snapshot? You use Clone when the experiment you are running was created from another user's profile. Since you do not own that profile, you cannot Snapshot. Clone it first, and then you have your own profile you can instantiate and then Snapshot.