Dropbox has stopped creating public folders for the new customers. Previously, whenever a new Dropbox account was created, a public folder was automatically added to the account. The public folder would allow any file in that particular folder to be publicly available. Anyone could access the file.
Here is a note from Dropbox:
New Dropbox accounts created after October 4, 2012 no longer have a Public folder. Don’t worry! Every account created prior to this date will still have a Public folder.
The users who were used to using the public folder would have seen that their public folder was being indexed by Google and therefore all their files in the public folder could be seen and accessed by anyone.
So Dropbox decided to stop creating the public folders by default. This will only affect the new accounts. The users who have already created accounts and are using the public folders will not be affected.
New Dropbox users will be able to use the file sharing feature of Dropbox. You can right click any file in the Dropbox folder and share the file from the Dropbox context menu.
To see which of your files are publicly available, you can follow this link which lists down all the files in public folder. Please note that you need to be signed in to see all your public files via the above link.
Most Dropbox users don’t even need the public folder or even the file sharing capabilities but if you are desperate to use the public folder of Dropbox, you can re-enable it on your new account by visiting this link.