Microorganisms are tiny living organisms found everywhere—in air, water, soil, and even inside our bodies. They include bacteria, fungi, protozoa, algae, and viruses. Some are beneficial, helping in food production, medicine, and agriculture, while others cause diseases and food spoilage. Microorganisms play a key role in nitrogen fixation, environmental cleanup, and food preservation. Proper hygiene and vaccination help prevent the spread of harmful microbes.