An alias is a "shortcut" that allows you to open files, folders, servers, or applications that you use often. You can specify a color for aliases to identify them in a list.
You can view, select, copy and move files or folders in a folder that are aliases when the alias is visible; however, when you copy a group of folders that contain aliases, the aliases will be ignored. You are prevented from downloading these "hidden" aliases because it is possible for the alias to be linked the initial folder; if you were able to download a "loop-linked" folder, the download would never end. To prevent this from happening, you can only download visible aliases.