If you want a real backup, then I presume you don't want to compromise the picture quality in doing so. If you reduce the quality, you can never recover and may regret that at a later date should you wish to have them printed.
The likes of Picassa and others will allow you store photos online at their original quality. There are also a number of cloud base backup solutions that allow you backup all important information online.
You can also get network attached drives that will allow you to automatically backup all important files on your laptop, and make them available to any device on the network (other laptops, phones, tablets, smart TV, etc.) Some will allow you access when you're away from home.
If all you need is to have a safe backup of your photos so that you can retrieve them if your hard drive fails, then a couple of portable external hard drives are hard to beat for cost/convenience. I say a couple, as you can store one elsewhere so that you still have a copy should one drive fail, get stolen, damaged in fire, etc.