Actually, I'm kidding. Back in the day, floppy disks were the most common way to back up your files, but they've been mercifully obsolete for many years now. I hope that bringing these relics up doesn't date me too badly--but in my defense, last year my dad asked me if using floppies was a practical backup strategy for his photos. That's when I pointed out to him that my last few computers didn't even come with floppy drive bays (which makes it all the stranger that I have a stack of floppies still stacked neatly on a shelf, "just in case").
The most common floppy disks have a capacity of 1.44MB, which means that you'd need a stack of about 700 floppies to store all the photos on just a single 8GB Secure Digital card.
So if a mountain of floppy disks won't do the trick, what other options do you have?