Carbonite is one of the web's most popular online backup services, and for good reason. The Carbonite client runs quietly in the background uploading your data to Carbonite's servers to make sure it's safe in case something happens to your computer. Carbonite can automatically back up documents, music, email, and other files (although it manually backs up video), and grants you access to those files and your archives on your smartphone. Carbonite supports Windows and OS X (although its Home Plus and Home Premier plans only support Windows), and make restoring your files as easy as backing them up. Your offsite files are encrypted to keep them safe from prying eyes, and all of their plans include unlimited storage for your backed up files. Carbonite's Home Plus plan extends its features and allows you to back up external hard drives and not just files on your computer, and allows you to back up full system images. The Home Premier plan includes both of those features and adds automatic backup of your video files, and a courier recovery service that delivers you backups on a hard drive to you ASAP if something terrible happens.
Most services encrypt your files with strong systems such as AES 256 before sending them up to the servers over an encrypted connection. The majority of products we tested also offer a private encryption key option. If you choose to manage your own encryption keys (basically the "key" that decrypts your backup), know that it is your responsibility to remember it. The online backup service itself will not be able to help you reset the password if you forget it. On the flip side, this means that no one (including employees of the backup service and law enforcement officials) other than you can unlock your backups. This is ideal from a privacy and security standpoint. Use a password manager to keep track of your private encryption key if you think you will forget it.
Online backup services scan your hard drive for files worthy of protecting, encrypt them for security, and send them up to the company's online servers. Once your files are uploaded, you can access and restore your data from anywhere. Though there's some overlap, online backup services shouldn't be confused with cloud storage and file syncing services like Box, Dropbox, Google Drive, OneDrive, and SugarSync. Those services do store files in the cloud, but they aren't designed to automatically protect all important documents and media files, let alone system files. Their strategy is generally to sync just one folder with all its subfolders to the cloud, and in some cases, to offer online collaborative document editing. Many backup services offer folder-syncing capabilities, but few syncing services offer full-scale backup functionality.
Bitcasa Infinite Drive is relatively new, but it's one of your favorite cloud storage providers in general, mostly because they offer virtually unlimited stroage for syncing and backups. When we say unlimited, we mean it—some of you are using terabytes of storage with Bitcasa. It's not primarily a backup service though, and while it was built for file syncing and storage, the Bitcasa desktop client does support regular file backups. Bitcasa supports Windows and OS X, and encrypts all of your files before uploading so they stay safe from prying eyes. Bitcasa even keeps revision history, so if you've backed up a file multiple times and need an older version, you can pick it out and restore it. Plus, you can use the Bitcasa mobile apps for iOS, Android, and Windows Phone to access your data on the go.