Blood was a bodily fluid that many species had. It provided a way for the body to transport oxygen, nutrients, waste and other things vital to survival over the body. The color of blood varied between species. Most species, including Humans, Chiss, Zabraks, and Aqualish, had red blood. Duros, Falleen, Rodians, and Trandoshans had green blood, T'surr, Rattataki and Talz had blue blood, Geonosians had yellow blood, Judd's species, Devaronians, Aleena, Massassi and Yuuzhan Vong had black blood.
According to Han Solo, the taste of blood was roughly equivalent to the taste of liquid tin. A blood transfusion from a Force-sensitive to a non-Force sensitive would not grant the latter a connection to the Force. In 3645 BBY, Sith Lord and alchemist Darth Scabrous used a backpack-mounted intravenous device to transplant uncontaminated blood when he was infected by a zombie-creating virus known as "the Sickness". This slowed the rate of transformation, allowing him to survive much longer than others who were infected.