Microbiology is the study of microscopic organisms like bacteria, viruses, fungi, protozoa and algae. It examines their classification, physiology, distribution in nature, and relationship to humans and other organisms. Microbes are found nearly everywhere and can be beneficial or harmful to humans. They are essential to food production, industrial applications like antibiotics, and recycling of elements in agriculture. Key discoveries in microbiology history include the first observations of microbes by van Leeuwenhoek and Hooke, establishing fermentation and diseases as caused by microbes, developing techniques like staining and pure culture isolation, and discovering important pathogens and antibiotics.