There are many ways to categorise computer backups: based on what you back up, on how you make your backups and on where you store your backups. Each type of backup has advantages and disadvantages. For complete security, you may need more than one type of backup.

1.  File Backups

o    The most common form of backup copies your files (photos, documents, videos, spreadsheets---also known as your data), but not your software or operating system, from your computer to another drive or some form of storage media. Your data is the hardest thing to re-create or replace if your computer is lost, stolen or destroyed, so it's the most important thing to back up.

Full vs. Partial Backups

o    A full backup backs up all your files. A partial backup, usually known as an incremental backup, backs up the files that have changed since the last time you performed any kind of backup. A differential backup backs up the files that have changed since your last full backup. Most backup software makes a full backup the first time you use it and incremental backups thereafter.

System Backups

o    A system backup backs up your operating system and installed software, as well as your files. File backups protect against accidental deletion or corruption of your files, but if your entire drive fails, you'll need to reinstall the operating system and software before you can put your files back on the computer---unless you have a system backup.

Drive Images

o    A drive image, also known as a "clone," or a "disk image," preserves a mirror image of your entire hard drive at a specific point in time in a single file. Drive images make restoring your computer after a drive failure very fast, but they often take hours to make. Drive imaging software also uses proprietary formats, which can make restoration harder.

Continuous Data Protection

o    Rather than making a backup of all your data at once on a set schedule, a continuous data protection (CDP) system backs up your files as they change. This may slow the system down a bit, but never takes it offline entirely. CDP also preserves the greatest amount of data in the event of a system failure, because there is the shortest delay between backups.

Onsite vs. Offsite

o    A backup that you keep onsite, that is, in the same location as the computer you're backing up, is the quickest one to restore in the event of data loss. Unfortunately, it's also vulnerable to many problems that might affect the computer you're backing up, such as theft, fire or natural disasters. That's why it's good to have a second backup stored offsite. Individuals store offsite backups with friends or in safe-deposit boxes; enterprises hire third-party services that specialise in secure records storage. Offsite backups may be at risk of theft while in transit to their storage location, so it's a good idea to encrypt them.

Online vs. Offline

o    Backing up your files online (over the Internet) gets them offsite and out of your home and office, but in most cases online backup is only feasible for your most important files, due to monthly bandwidth caps and restrictions that ISPs impose on upload speeds. Offline backup can refer to backups stored either onsite or offsite.