Just about everything we eat, touch, and see contains organisms too small to be seen with the naked eye.  This video explores the fascinating world of microscopic life.  It begins by discussing viruses and explaining how these cause disease.  Bacterial cells are described, highlighting the important roles they play on Earth.  The video pays special attention to protists, comparing the structure and function of plant-like, animal-life, and fungus-like protists.  Additional concepts and terminology: microscope, vaccine, moneran, decomposition, amoeba, phytoplankton, yeast, algae, paramecium, and protozoa.