Bacteria

Bactérie
©iStock.com/Henrik5000

Tiny living organisms that are made up of a single cell that does not have a distinct nucleus, such as a prokaryotic cell. Due to their ability to colonize even the most extreme environments, bacteria are all around us. Some bacteria (germs, or microbes) are harmful to human beings and can trigger disease, but other bacteria — such as those found in the intestine that aid digestion — are beneficial.