Learn microbiology the way it is actually taught — the microbes and how they cause and are fought. Start with the major groups (bacteria, viruses, fungi, parasites) and what sets them apart, then master the tools that classify bacteria (Gram-positive vs Gram-negative, cocci vs bacilli, aerobic vs anaerobic), how microbes spread and cause disease (transmission, virulence factors, exotoxins vs endotoxins), and how the immune system, vaccines, and antimicrobials counter them — including why antibiotics fail against viruses and how resistance arises. Each question teaches the mechanism and names the classic mix-ups (virus vs bacterium, Gram stain colors, colonization vs infection). Built on the free OpenStax Microbiology corpus — great for nursing, allied-health, and pre-med review. Educational only — how microbes and infection work in general, NOT diagnosis, treatment, or medical advice; individual care belongs to a qualified professional.