By: Christopher Thomas

The flu. We've all heard of it, and we've all had it at some point, and we all equally hated it. Having the flu stinks -- it makes you nauseated and runny-nosed and achy and miserable. The flu has been around since the beginning of time, but over the years it has changed. New and different strains of the flu are popping up all over the world, and some of them are meaner and scarier than ever before.

The flu is a virus, not a bacteria. To understand how the flu spread and grows you need to understand what it does once it is in a body.