Cyanobacteria, often referred to as blue-green algae, are a group of photosynthetic bacteria found in various environments, including freshwater, marine, and terrestrial ecosystems. They play a crucial role in producing oxygen and are among the oldest living organisms on Earth, dating back over 3 billion years. These microorganisms can form blooms in nutrient-rich waters, which can lead to harmful effects on aquatic life and water quality. Some species of cyanobacteria produce toxins that can be harmful to humans and animals, making monitoring their presence important for environmental health and safety.