Microorganisms are tiny living organisms that can only be seen with a microscope. They include bacteria, viruses, fungi, and protozoa. Despite their small size, they play a crucial role in our environment, helping with processes like decomposition and nutrient cycling. Some microorganisms are beneficial, like those found in yogurt that aid digestion, while others can cause diseases. These tiny creatures are found almost everywhere, from the soil in our gardens to the water in our oceans. They can survive in extreme conditions, such as hot springs or deep-sea vents. Understanding microorganisms is essential for fields like medicine and environmental science, as they impact health and ecosystems.