How do viruses spread?

Viruses can spread in a variety of ways, unfortunately. Through your network, within downloaded content and from disk to disk, including flash drives. Sometimes viruses are even hidden within software that you deliberately install into your system. However, viruses can't spread on their own; they need some help from a knowing or unknowing user. The most common ways viruses are transmitted is through email and through Internet downloads, so be careful what you accept into your system. You can't be too careful when the functionality of your whole computer is at stake.