There's two options for backing up. Disk imaging and Snapshots.
Disk imaging is good, the image can be stored off site making it reliable but you need to buy storage media (i.e. CD's, DVD's, External Hard Drive, USB, etc) to store it's image and it's also a very time consuming process, with the generation of a snapshot taking 45+ minutes minimum, and re-imaging taking 2+ hours. Programs like Macrium Reflect and Drive Cloner Rx work well for this.
Then there's Snapshots. They're a lot faster and easier to take, usually it takes a few seconds to take a snapshot, and a few to restore. The only downside is that they are on your hard drive, so if you have a hardware failure. Examples of this type of software are Comodo Time Machine and...