Private folders work just like any other folder on your hard drive. Move, copy, and rename the folders and its contents just like you would any other folder. As long as the folder is in the Dropbox folder, and Dropbox is running, everything in it will be synced online and to your other computers.
Private folders can't be accessed publicly. Everything in these folders is as secure as any other file on your hard drive and accessible via dropbox.com only if you're logged in. Private folders can become shared folders, and you can share files in a private folder using shared links.
Shared folders and their contents are available only to those you invite. You can make any normal folder a shared folder, or you can accept someone else's invitation to join their shared folder. When you share a folder, you're prompted to enter the email addresses of those you want to share your folder with. Once the recipients accept your invitation, the shared folder appears in their Dropbox account just as it does in yours. Any changes made to the shared folder are synced to anyone else who joined the folder. It's a great way to collaborate on a project and/or share files with others.
You can prevent other members of your shared folders from adding, editing, or deleting files by setting view-only permissions.
Windows and Mac only
Use the Dropbox badge to see if your file is in a shared folder. Clicking on the Dropbox badge opens a pop-out window where you can see the number of people sharing the file with you.
Click on Shared Folder Settings in the Badge to go to dropbox.com. On dropbox.com, you can view the names of those you share the folder and file with.
Unlike shared folders, linked files and folders are read-only, meaning users can view and download them, but can't change their contents.
Shared links are unique to your account, and while it's highly unlikely that people could ever guess the link, the links themselves are transferable and could be viewed and downloaded by anyone with or without a Dropbox account.
Links to folders allow outside access not only to the folder and its contents, but any sub-folders and files inside those sub-folders, too.
On dropbox.com, you can easily see which files and folders you've shared a link to in the past: a link icon will appear under the Shared with column.
Dropbox Professional and Dropbox Business users
Some third party apps with Dropbox integration will ask for permission to access your Dropbox account. To grant access, you'll need to log in to your Dropbox account and explicitly click the Authorize button when prompted. You can visit the Apps linked section of your account settings to review the apps you've granted permission to and revoke access at your discretion.