There are few things as terrifying as the dreaded "click of death" from a hard drive. That's if you KNOW what a hard drive is, and what the sound means!
It's all of your data, contacts, pictures, programs and files....gone. Probably unrecoverable.
The hard drive is not the big box that has everything in it. It's a small metal case deep inside the big box, that stores your information permanently. Or not.
They are relatively easy to get to and replace. The only sure way to protect what is on them is to BACK UP YOUR DATA. This means that every (month - week - day) you get your computer to save an extra copy of your valuable files somewhere safe, like on an external drive, a DVD or CD, or even in cyberspace (in the "cloud"). It takes discipline to do it, but it's time well spent if something goes wrong with your system!
Coming below will be a pictorial guide to both backing up and replacing your hard drive. I'm about to do it for my own system - it's well overdue....