Dropbox is an online backup / syncronization utility that synchronize any files inside the Dropbox folder to Dropbox's servers and any other computer linked to your account. It uses SSL and encryption when it transfers your files to protect against interception. It keeps different revisions of changed files which allows you to easily restore a previous version. You can also access your files from the Dropbox website, allowing you to retrieve files on a computer connected to the Internet without having to install Dropbox on that computer. You can put files into a public folder which allows you to share them over the Internet, allow only certain users (collaborators) to edit files, and create photo galleries. For a better overview of how Dropbox works, check out the tour on thier website. Dropbox has clients for Windows, Macs, and Linux.
