Data Backup Software and Service

Two basic kinds of software facilitate the latter approach: specialized backup software and synchronization programs.

(See Wikipedia for a fairly thorough, though slightly geeky, explanation of the entire backup subject.)

For this backup software roundup, I looked for programs with these capabilities (and so should you):
Select files, folders, or entire drives for backup.

Select or exclude files according to file extension masks (for example, *.doc, *.xls, *.dat, etc.). The built-in mask should already know how to find Outlook, Outlook Express, and other common applications’ data files (for instance, *.pst and *.pab).

Support multiple backup "sets" or "profiles".

Either incremental or differential backup or both, in addition to full backup.
Set up an automatic schedule for unattended backups.
Back up the Windows Registry.

Automatically save and close open files so they can be backed up.

Copy files as they are, or archive them using ZIP compression. (Use of this universally accepted file format ensures that you can restore your files even without the backup program that created them.)
Protect backup files using ZIP encryption.

Protect backup files with a stronger encryption method (such as DES, AES, Blowfish, etc.). (Warning: Strong encryption can require the backup program for a restore… and don’t lose that password!)
Copy to CD or DVD, hard drive, flash drive, networked computer, or an FTP site on the Internet (even if not secure).

Keep a log of backup and restore operations, and send email notifications on completion.

Other desirable features include enabling you to specify other programs to run before or after the backup, excluding already-compressed files (such as *.zip, *.jpg, *.mp3, etc.) from compression, and verifying the integrity of backup files. Some also include synchronization functions, and a few can also create disk mirror images.