But I already backup my files onto the hard drive, why would I need additional backup?
Answer:
Although computers are perceived as reliable electronic devices, their main storage medium – the hard drive of a computer - are mechanical devices, and most hard drives will fail within five years. When a hard drive fails the stored data will be damaged, often irreversibly. ‘Backing up’ onto a tape means you have a second copy of your data that can be removed for safe keeping.