Many services also offer a feature called versioning. This saves incremental changes you make to files as recoverable snapshots of the file. It's useful in case you need to get back information from an earlier version or if your latest file save becomes corrupted. Services vary widely in how many versions they keep and how long they're saved. Best-in-class services, such as SOS Online Backup and SpiderOak ONE keep an unlimited number of file versions forever.
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.
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.
Real time: Real-time backup means that files are backed up whenever they change, usually upon creation or save. It’s also called mirroring and is handy for keeping an immediately available copy of rapidly changing data sets. For less volatile data sets, the payoff doesn’t compensate for the drain on system resources. Instead, scheduling should be used.