They say the first thing people grab from a burning house is their family photos, but what if all your photos are on your computer! For this and many other reasons it is so important to backup your photos. I highly suggest that you backup to several different sources such as; dvd, usb, portable hard drive or the cloud. I also suggest that you keep one backup source offsite (like at work) and keep one at home in a fireproof box. More reasons to backup to multiple sources is because computers crash, technology changes, and files become corrupt. One thing I do is set a reminder on my phone monthly to download and backup my digital files (including those images taken with my phone). It is better to be safe than sorry with our precious family memories!
This includes those digital files you purchased from a professional photographer!!