Bacteria

Bacteria are single-celled microorganisms that exist everywhere in the environment, including inside and on the surface of the human body. Bacteria are prokaryotes, meaning they are not organized into nuclei. Bacteria are typically less than 1 micrometer in size and can be found in nearly every habitat on Earth, from soil and ocean sediment to the human gut. Bacteria have an array of shapes, including spherical, rod-shaped, and spiral, and are capable of rapid growth and reproduction. Bacteria are essential to life and play a role in many important processes, such as decomposition and nutrient cycling in the environment, and food production and digestion in the human body. Bacteria can also cause illnesses and are responsible for a variety of infectious diseases. Bacteria can also be used to produce useful products, such as antibiotics, food additives, and enzymes.