Blood is a fluid component that is transported throughout the entire body via the circulatory system. Arteries transport oxygen and other nutrients to various body tissues. Veins transport carbon dioxide and other metabolic by-products to the lungs and kidneys respectively for eventual removal from the body. Blood, then, helps to rid the human body of toxins and enrich it with essential nutrients. Blood is composed of red blood cells, white blood cells, plasma, and platelets. Red blood cells are essential for cleansing the body tissues of toxins and enriching the body with nutrients. White blood cells, also known as leukocytes, prevent diseases and illnesses by fighting bacteria and other disease-causing germs in the body. Plasma, the liquid part of blood, is mainly made up of water. It transports water and essential nutrients to different body tissues. Platelets help control bleeding and heal wounds on the skin by actively forming clusters that protect the wound. Blood is grouped according to the blood type and the presence or absence of the Rhesus (Rh) factor. The different blood types are A+ or A-, B+ or B-, AB+ or AB-, and O+ or O-. A blood test can determine a person’s blood type.