Bacteria is a prokaryote and lies in the prokaryotic domain with archaea bacteria. They are unicellular, too.
The Good And The Bad
Good bacteria are called probiotics, and live in your body. Probiotics can be good for your health. They're in medicines and foods. Bacterias such as Lactobacillus and Bacillus Coagulans are examples of probiotics. Bacteria, even the bad ones, are actually one of the best decomposers!
Fortunately there's more good bacteria than bad bacteria. The bad bacteria can make you sick, and spoils your foods and drinks!! D: It's best to stay clean and healthy so the bad bacteria doesn't get to you. ;)
Wait. There's ugly bacteria?!
Ugly bacteria is so much badder than the bad bacteria!! There isn't that many, but they can have a big impact on you. Ugly bacteria is very contagious! It is the cause of horrible diseases such as the Bubonic plague (also known as the Black Death), leprosy, and cholera. Ugly bacteria can make a tiny flu SO MUCH WORSE!!!
My science spiral XD