Dropbox is a free cloud storage service that allows users to store and share files across all their devices. Users can access files from any device via desktop, web or mobile clients which are connected to secure servers. When files are added, changed or deleted on one device, they are automatically synced and updated on all other linked devices. To use Dropbox, a user creates an account and allows the service to create synchronized folders on all their connected devices. Files can then be shared with others by providing a link to the Dropbox folder.