Why is it important to have an external hard drive for backup?

People under estimate the importance of backup. Often computer users have to lose their files at least three times before they change their ways and backup all their files to an external hard drive.

Just think about it...An external hard drive stores all your files and is totally separate from your computer, therefore if any crashes occur, your files will be safe.

I am so cautious that I have two external hard drives for backup, just incase the first one has problems...I know this sounds crazy but I have seen it all...

Western Digital My Passport Essential 500 GB USB 2.0 Portable External Hard Drive WDME5000TN (Midnight Black)

Seagate FreeAgent Go 500 GB USB 2.0 Portable External Hard Drive ST905003FGA2E1-RK (Silver)

Seagate FreeAgent Go 500 GB USB 2.0 Portable External Hard Drive ST905003FAA2E1-RK (Black)