This is probably the most important type of backup, and the one that most people are used to. Here only documents, data files, pictures, music files and videos are backed up. If you are running databases of any type, database files should be included as well. The biggest questions are usually
– How often? How much data can you afford to lose?
– Are all my documents and data files being backed up? Do email files and database files need to be specially backed up? Are open documents being skipped?
– Can files be easily recovered from backup?
– Is it easy to forget to backup?
– Do you want to be able to recover earlier versions of files?
– How much space is needed to back up everything that is needed to be backed up?

A System Image backup will copy everything on your hard drive and treat it as a series of 1s and 0s instead of a list of files. The backup will include things such as partition tables, boot records, files system structure, the entire operating system, registry, and installed programs; all of which are usually ignored in a typical file backup. The backup file that is created is very large, but this type of backup usually does not need to be done often.
A system image backup is a good insurance policy, and if things go completely pear shaped they can be a quick and easy way of getting your computer up and running again. This backup type comes into its own if your hard drive dies, gets corrupted, becomes heavily infested with viruses, or even if you just want to replace your hard drive with a larger one. Formatting your hard drive, reinstalling all your operating system and programs, and applying all updates, can take a long time.
To recover your system, boot from a recovery image and replace the contents of your hard drive with the system image backup. Your computer will be restored back to how it was when the system image was taken. Documents and data files can then be recovered from your document backup to bring your computer completely up to date.
If your computer hardware is lost it is possible to convert many system image backups into a virtual machine. This means you can run your system as a virtual machine on another computer until you have a suitable replacement computer up and running.
Windows 7, 8, and 10 have inbuilt system image backups. Many other backup systems include system image backups by default.

An external hard drive is suitable for stand-alone desktop computers, but can be inconvenient for laptop and tablet users as the external hard drive needs to be unplugged when moving the device.  In the case of desktop PCs an additional hard drive can be installed specifically for backups.  The inbuilt backup software or third party software can be used.  The biggest disadvantage is that the backup drive can easily be stolen or destroyed at the same time as the computer; hence businesses tend to have multiple drives, with the most recent backup being taken off site.

It can be very convenient install a network device to store backups, especially when there are several computers on the same LAN.  These can range from a WiFi hard drive like the Seagate Wireless Plus Mobile Storage, to a NAS, to a full blown file and backup server with tape drive.  The advantages are that there is no need for laptop users to remember to plug in an external hard drive, backups from multiple computers can be saved in a central location, and if removable media is used businesses can ensure a copy of the backup is taken off site for safety.

Cloud backup services can be ideal for laptops, and small to medium business backups.  For laptops, it means you can backup your recent files wherever you are as long as you have an internet connection.  For a business it ensures that the backup copy is both off-site and it cannot be forgotten.  The downside is that the first backup will take a long time, typically several days, as upload speeds are much slower than download speeds. If a computer needs to be completely restored quickly a large download can seem to take forever.
Online backups are good for file backups, but system image backups should still be done locally, unless you have very fast Internet speeds and a lot of bandwidth.