When we think about viruses, we think about diseases such as the flu. For the most part, the flu comes and goes, the body is able to fight it. For some, it can be deadly. There are of course more dangerous viruses out there such as Ebola that in some cases kills 90% of those infected. In today's world, viruses can spread very quickly and it's for this reason we must be vigilant. Carl Zimmer in his book "A Planet of Viruses" discusses what viruses are and why they are so hard to eradicate, he also explains how not all viruses are bad and are, in fact, vital to our survival. Enjoy!