Hominid species refer to a group of primates that includes modern humans, our ancestors, and other extinct relatives. This group is part of the family Hominidae, which also includes chimpanzees, gorillas, and orangutans. Hominids are characterized by their ability to walk upright on two legs, known as bipedalism, and their larger brain sizes compared to other primates. Throughout history, several hominid species have existed, such as Australopithecus, Homo habilis, and Homo neanderthalensis. These species show a range of physical and behavioral traits that highlight the evolutionary journey leading to modern humans, Homo sapiens. Fossil evidence helps scientists understand how these species adapted to their environments and interacted with one another.