Oh No! I lost my folder! The difference between "Add" and "Move" in Google Drive.

It's very easy to drag to files and folders around in Google Drive, too easy in fact, and dragging items in a shared folder moves them from everyone who is part of the folder...so ... Let's look at the steps that will prevent this from happening.  But before, let's understand the difference between "Add to" and "Move"

One of the best things that Google Drive offers is the ability to have a folder structure in which subfolders are housed in top level folders.

Let's say you have a folder structure with 4 sub folders and you move one of those sub folders to your "My Drive" for easy access.  Great! but be careful you do not move the folder for everyone else.  A simple way to make sure you keep the folder structure in place is always press CTRL and then drag.
Alternatively, use the "move to" menu item.  Both of these actions will actually "Add" a folder rather than "Move" the folder- this is how Windows handles it too.

So dragging without pressing CTRL will remove the folder from everyone else who the item was shared with.

Best practice is to use the "Add to my drive" menu option or if you want to manually drag, don't forget to click CTRL and drag as you hold down CTRL.

Setting permissions to your folders is also recommended but setting the permissions will not prevent the other users to drag the folder to their Drive.

Click here to see how to "Add to my Drive" in the new Google Drive.  If you have not switched yet, here's a handy Cheat sheet to learn and get used to the New Google Drive.