What are the four spirits in ancient Chinese legends? And what is the meaning?

Ancient people regarded the four spirits as the first of the auspicious, in ancient Chinese mythology, the green dragon, white tiger, vermilion bird, Xuanwu are the four gods. They are guardian gods, have to suppress demons and evil spirits, blessings and drive away the divine power, by the people's worship and adoration. Oriental wood, its star Canglong, the jurisdiction of the East seven hosts, horn, hyper, the clan, room, heart, tail, Kei, on behalf of the four elephants or four palaces of the spring. Western gold, its star White Tiger, the jurisdiction of the western seven hosts, Kui, Lou, stomach, Ang, Bi, mouth, Sam, on behalf of the four signs or four palaces of the fall. Southern fire, its star Zhu Bird, the southern seven sleepers, wells, ghosts, willow, star, Zhang, wings, square, representing the four elephants or four palaces of the summer. Xuanwu is a turtle and snake, located in the north, so it is called Xuan, the body has scales and armor, so it is called Wu. Zhu bird before the south, Xuanwu after the north, Qinglong left east, white tiger right west.