Tara C. Smith has written an excellent introduction to microbiology which will be of use to educators and all microbiologists who find themselves explaining microbiology to the uninitiated.

The article divides microorganisms into viruses, bacteria, fungi, and protozoans and discusses each category briefly, touches on prion diseases and finishes up with a brief introduction to the immune system. The article is really useful to help you explain microbiology to laymen who may not realize the differences between a bacterium and a virus, much less the smaller differences between, for example, a pathogenic versus a commensal organism.