Bacteria are among the simplest living organisms around. They don’t have cell walls, but their DNA is not organized and they’re not very big. They can take on any number of shapes (sphere, rod, etc) and can live nearly anywhere. They reproduce by dividing in half, so there are practically millions of them wherever you go.
Bacteria are shaped in circles, pill shapes, spirals, and corkscrews. Some bacteria have cell walls on the outside, but most do not although they are bound by some sort of cell membrane. Within the membrane, bacteria have a cytoplasm in which their DNA floats around. Sometimes, pilli surround the outer capsule and are designed to help the bacteria attach onto cells more easily. Some bacteria even have a floppy tail end called a flagellum which helps it to move around.
Bacteria aren’t all bad, even though they do tend to cause disease. Bacteria in our intestines helps our bodies digest food, and bacteria are also used to make medicines, foods, and cosmetics.