Microbiology is the study of microscopic organisms, such as bacteria, viruses, fungi, algae, and protozoa. It explores their structure, function, genetics, evolution, and roles in health, disease, industry, and the environment. Key branches include medical microbiology (infectious diseases), environmental microbiology (ecosystems), industrial microbiology (biotechnology), and microbial genetics. Microbiology has applications in medicine, agriculture, food production, and biotechnology.