Backing up your valuable photographs is a really important task that so often gets forgotten until it is too late. Incorporate this into your digital workflow.
Being extra cautious/paranoid with my extensive library of images I have 3 external hard drives with a back up of all my images on each. For extra safety when leaving the house one of the hard drives goes with me.
There are lots of solutions as to where to back up your images, choose the one that`s best for you and remember to back up regularly.