Dropbox is a cloud storage and file sharing service that allows users to access and share files across multiple devices. Files stored in Dropbox are automatically synced and accessible from computers, phones, tablets and the Dropbox website. Dropbox offers 2GB of free storage that can be expanded by inviting friends or upgrading accounts. It provides an easy way for users to backup, share, and access important documents, photos and files from any device with the Dropbox app installed.