Cyanobacteria, also known as blue-green algae, are a group of photosynthetic bacteria that obtain their energy through photosynthesis. They are found in various aquatic environments, including freshwater, marine, and even terrestrial habitats. Cyanobacteria are characterized by their ability to produce oxygen as a byproduct of photosynthesis, similar to plants. They are considered one of the oldest forms of life on Earth and have played a significant role in shaping the planet’s atmosphere and ecosystems. Some species of cyanobacteria can form colonies or filaments, giving them a distinctive appearance. While many cyanobacteria are harmless, some species can produce toxins that are harmful to humans and animals, leading to harmful algal blooms in water bodies.