We live in a world of germs (better known as microbes). Multitudes of them live in our own bodies. Yet most of them do not cause us harm. They help us in digesting and processing the food we eat. Others help us fight off tooth decay while still others are involved in helping to activate our immune system (the system that fights other germs that cause diseases). How is this possible? Most of us have thought of germs as mostly being harmful, causing many infectious diseases that always must be cleansed from our bodies by anti-bacterial agents. However, in the past 100 years or so, scientists and physicians have learned how to fight and indeed conquer most of them by stimulating our own immune system as well as by remarkable outside treatments such as the use of antibiotics (which amazingly enough also are produced by microbes). In order to understand the nature of these remarkable one-celled organisms, both good and bad, we will discuss what they are in scientific (but easily understood) terms, the reasons that some of them cause infectious diseases, and why we are being confronted now with many emerging (new) and reemerging (not new) infections. We will consider as well the myths and realities of treatment for some of the more dangerous or well-known pathogens.