Vertebrata is a subphylum of the animal kingdom that includes all animals with a backbone or spinal column. This group encompasses a wide variety of species, including mammals, birds, reptiles, amphibians, and fish. Vertebrates are characterized by their complex skeletal structures, which provide support and protection for their internal organs. Vertebrates are further divided into different classes based on their unique features and life cycles. For example, mammals are warm-blooded and usually give live birth, while fish are cold-blooded and typically lay eggs. This diversity allows vertebrates to inhabit various environments, from oceans to forests.