Avatar Aang was a male Air Nomad and the Avatar during the century-long conflict known as the Hundred Year War. His immediate predecessor was Avatar Roku, and his immediate successor is Avatar Korra. Aang was the only person in the Avatar World who could use all four bending disciplines: airbending, waterbending, earthbending, and firebending. He was also one of a select few Avatars, and one of the first in many cycles to learn the ancient art of energybending. Aang was the first Avatar seen using the technique; the second was Avatar Korra, seventy years later. Shortly before the beginning of the Hundred Year War, Aang was frozen in an iceberg for a hundred years. He emerged, still biologically twelve years old, into a world engulfed by war. During his absence, the Fire Nation had waged war upon the other nations and managed to completely wipe out the pacifistic Air Nomads. It fell to Aang, the last airbender and the Avatar, to put a stop to the War by mastering the other three elements and defeating the Fire Lord, Ozai. He remained something of a goofy, kind kid at heart throughout this year-long struggle, despite the overwhelming loss of his people and the heavy burdens he had been forced to bear. After his victory over the Phoenix King, Aang began a romantic relationship with his close friend, Katara. The couple eventually married and raised a family, which includes three children: Kya (a waterbender), Bumi (a non-bender), and the youngest, Tenzin (an airbender). Aang as a newborn.Aang was born to two unknown airbenders in 12 BSC who gave him to the monks of the Southern Air Temple. As an Air Nomad, Aang traveled extensively around the world. During his childhood, Aang was housed, raised, and educated at his home, the Southern Air Temple, under the custody of Monk Gyatso, who served as both a father figure, counselor, and teacher for Aang. As a child, Aang was a member of the Air Scouts, where he learned essential skills such as how to tie reins to a bison's horns with the bison horn knot. When Aang turned six years old, he and several other young Air Nomad boys were taken to the Eastern Air Temple where they each chose a sky bison as their lifelong companion. Aang approached his soon-to-be pet sky bison Appa and offered him an apple, which Appa accepted, thus marking the start of their long, deep friendship. Aang had always been able to excel with any new bending moves he learned; at the age of six, he was a better airbender than children twice his age, and by the age of ten, Aang had proven himself to be better than his own teacher.
While still a young boy, Aang had unknowingly revealed himself to be the Avatar when he chose the four Avatar relics out of thousands of various toys. In his childhood, Aang also visited the other air temples, as evidenced by his obvious familiarity with the Western Air Temple, as well as cities in the then-peaceful Earth Kingdom, such as Omashu, where he developed a lasting friendship with the good-natured but eccentric Bumi. He even bonded closely with children in the Fire Nation, like Kuzon, with whom Aang claimed to have gotten "in and out of so much trouble together". Due to the signs of a possible war approaching, Aang was told about his status as the Avatar at age twelve, four years earlier than the traditional age of sixteen, after exhibiting prodigious talent with his native element, air. Aang felt burdened by his status and came to spend more time practicing airbending with the monks rather than playing with his friends as he was used to. Monk Gyatso was the only one to show understanding to Aang's burden, having been good friends with Avatar Roku, Aang's past life, and tried to help ease Aang through the transition from childhood to adulthood by providing Aang with balance through fun during the upheaval in his life.
However, soon after learning that he would be sent to the Eastern Air Temple in order to complete his airbending training far away from Monk Gyatso, who other monks thought was too soft on him, Aang attempted to run away on his flying bison Appa. Shortly after running away, Aang and Appa were caught in a storm, crashing in the water and being swallowed by the waves. Aang saved himself and Appa while semi-consciously entering the Avatar State, freezing the two in a sphere of ice by using a combination of airbending and waterbending. The Avatar State kept him alive, albeit not fully conscious, in the iceberg for about a hundred years while the war raged on.