Dropbox is a cloud storage service designed to be an invisible app, providing users with a folder on their computer that automatically backs up and syncs files across all devices and in the cloud, allowing access from any computer worldwide. Users can use Dropbox to create backups, share files with teams, and send large files via email. The desktop app creates a folder where files are synced across devices, and users can add files to this folder using their computer's file browser or by uploading them directly through the web interface. Dropbox offers various features such as selective sync, online-only storage, and camera uploads, allowing users to customize their experience and automate tasks with Zapier's integrations. The mobile app enables users to browse and view files, but not download copies, unless necessary for sharing purposes. Sharing files is a crucial function of the service, offering multiple ways to share files directly from the computer or through links. By setting up selective sync, users can choose which folders to sync on specific devices, ensuring they only have the files they need available.