DROPBOX

Web-based file hosting service operated by Dropbox, Inc. that uses cloud computing to enable users to store and share files and folders with others across the Internet using file synchronization. It was founded in 2007 by Drew Houston and ArashFerdowsi.
There are both free and paid services, each with varying options.  In comparison to similar services, Dropbox offers a relatively large number of user clients across a variety of desktop and mobile operating systems. There are a total of 10 clients, including versions for Microsoft Windows, Mac OS X, and Linux (official and unofficial), as well as versions for mobile devices, such as Android, iPhone, iPad and BlackBerry, and a web-based client for when no local client is installed. Dropbox uses the Freemium financial model and its free service provides 2 GB omjf free online storage.  The service's major competitors include Box.net, Sugarsync, Mozy, and ZumoDrive.

Functionality
The Dropbox client enables users to drop any file into a designated folder that is then synced withDropbox's Internet service and to any other of the user's computers and devices with the client. DropboxUsers may also upload files manually through a web browser. Through these usages, it can be analternative to couriering physical removable media, and other traditional forms of file transfer, such as FTP and e-mail attachments.
While Dropbox functions as a storage service, its focus is on synchronization and sharing. It supportsrevision history, so files deleted from the Dropbox folder may be recovered from any of the syncedcomputers. Dropbox's version control also helps users know the history of a file they may be currentlyworking on, enabling more than one person to edit and re-post files without complications of losing itsprevious form. The version history is limited to 30 days.

 http://www.dropbox.com/