Did you know, bacteria are a living and thriving species? According to livescience.com, “There are over ten million different types of bacteria! They can live within soil, in the ocean, or inside the human gut.” I am very interested in seeing what type of cleanser best kills these bacteria. Hands are most in contact with the germs and bacteria of the outside world. It is really easy to come into contact with different bacteria and to pass them to other objects and people. Therefore, I am going to be testing to see if hand soap or hand sanitizer kills the most bacteria on the hands. Bacteria can be harmful at times, but can also be helpful. According to enotes.com, some that are helpful include “E. Coli are found in the intestines of humans assist digestion. Streptomyces is used in antibiotics. Rhizobium are found in the soil and help convert nitrogen in the soil.” On the contrary, they can be very harmful at times. “E. Coli can be harmful if you eat or drink a substance that has been contaminated by it. Listeriosis can make people extremely sick and can eventually lead to death. Listeriosis can be found in shellfish, cold cuts, and unpasteurized milk. Salmonella is extremely dangerous and lives in the intestinal tracts of humans. Poultry and eggs are some examples of food that can be contaminated with salmonella and can cause severe diarrhea. Others can cause tuberculosis and anthrax.” A human’s body holds many different types of bacteria that can help protect itself against the other harmful bacteria. It is said to be that there is approximately five million trillion trillion species of bacteria. Many scientists estimate that if they would line up the bacteria in a row, the bacteria would stretch to be about the same distance as ten billion light years. Bacteria was first discovered by Antonie van Leeuwenhoek in 1674. Many different species of bacteria still have yet to be identified.