Over a 100 years ago
When Aang was still young, he was given a bunch of toys to choose from. Based off of the four toys that he chose, it was revealed that he was the new Avatar, the one who would master all four elements. Aang was raised by the Airbending monks in the Southern Air Temple.
Soon after discovering he was the Avatar, his friends didn't want to play with him because they thought he had an unfair advantage in games. The only one that wanted what was best for Aang was Monk Gyatso. The other elder Monks thought their relationship was dangerous to Aang's development as the Avatar and decided to send him to the Eastern Air Temple to further hone his Airbending prowess. Scared and confused, Aang took his flying bison, Appa, and ran away. As he was traveling away from the Southern Air Temple Aang got caught in a storm near the south pole. In attempt to save himself and Appa, Aang entered the Avatar state and froze him and Appa in ice with a combination of Airbending and Waterbending.
100 years later/Book 1: Water
While fishing, Katara and her brother Sokka found Aang in the block of ice. They took him to their Water Villiage. While playing around Aang set off a trap that revealed his location to Prince Zuko, a Fire Nation prince who was sentenced to hunting down the Avatar. When Zuko arrived, Aang turned himself in so the Fire Benders wouldn't attack the people of the Water Village.
Katara and Sokka went after Aang and helped him escape and flew away on Appa. The three then started heading to the North Pole so Katara, a water bender, and Aang could learn water bending together. On their way, they came across the Southern Air Temple and Aang finally believed that he was the Last Airbender. All of his friends had been killed by the Fire Nation. Enraged he entered the Avatar state and unintentionally began surrounding himself with powerful winds. He finally came out of the state when Katara managed calmed him down.
The North Pole
When "Team Avatar" finally made it to the North Pole, Aang is introduce to Pakku, who is a water bending master. He said that he would teach Aang water bending and also agreed to teach Aang's friend. But when he found out that Aang's friend was Katara, a female, he declared that he would not for women were forbidden to water bend in the Northern Water Tribe. After a duel with Katara and learning of her grandmother, Pokku changed his mind and agreed to teach Katara too.
This would not last very long because soon after the Fire Nation began attacking the North Pole. In an attempt to learn the forms of the moon and ocean spirits, Aang enetered the spirit world. While in the Spirit World, Zuko attacked Katara and kidnapped Aang's body. While in the Spirit World, Aang had to go see the spirit Koh. After learning who the spirits were from Koh, Aang returned to his body only to find he is kidnapped by Zuko. Zuko was too weak to stop him from escaping when Aang's friends showed up. By the time Aang makes it to the spirit of the Ocean and Moon, he is too late. General Zhao, kills the spirit of the moon, which triggers Aang to enter the Avatar State. While in the state, Aang was able to defeat the Fire Nation Navy Fleet by himself.
Book 2: Earth
After his victory at the North Pole, Aang's next stop is to head to Omashu to learn Earthbending. Before they do they make a stop at and Earth Kingdom base where the General there thinks that Aang should enter the Avatar State and defeat the Fire Lord now. After many attempts, avatar Roku's spirit comes to Aang to tell him what the Avatar State is. It is the spirit, knowledge, and power of ever past life of the Avatar. But if Aang is killed in the Avatar State, the Avatar will be gone forever.
After finally making it to Omashu, Aang learns that the great Earth Kingdom city has been taken over by the Fire Nation. After sneaking in Aang is captured by the resistance there, and helps them escape from the city. Aang then continues his search for a teacher.
While in search for a teacher, Aang comes to see and Earthbending tournament where he sees a blind bender easily defeat her opponent. Aang thinks that she would be the perfect teacher and after doing some research finds that her name is Toph and where she lives. When going to her house, they find that she has over protective parents, but they are eventually able to get Toph to agree to train Aang.
While traveling the group came across a library, where a great spirit named Wan Shi Tong has gained all kinds of knowledge of the world. Toph decided not go in because, she can't read the books or see in the library. Wan Shi Tong was initially fairly hostile towards the children, but agreed to let them use the library after they promised no to use its information to harm anybody. While the others were in the library, they discovered that the next solar eclipse would make the Fire Nation helpless. When Wan Shi Tong learned that they were using its information to defeat an opponent he decided to bury the whole library with them in it. Toph tried to hold the library up with Earthbending. While she was doing this, some Sandbenders came and kidnapped Appa.
Aang is furious and blamed Toph for not saving Appa, and leaves the group to search for him. But after searching for hours he eventually returns to the group. They finally make it through the desert where Toph identifies the Sandbenders. Aang enters the Avatar state and demands to know where Appa is. Scared, the Sandbenders tell them that they traded him and that he should be in Ba Sing Se already where he will be sold.
Ba Sing Se
On their way to Ba Sing Se, they come across some refugees who tell Aang and his friends of a Ferry that can take them to Ba Sing Se. With Toph's status as a Bei Fong, they are able to get passes but Aang learns that the refugees who helped them got rejected. Aang tells them that he will help them through the Serpent's Pass. After many trials through the passes Aang and his group make it through the pass and to ba Sing Se.
While approaching the Great Outer Wall of the city, Aang sees a Fire Nation drill attempting to cut its way through the wall. Aang and his friends stop the drill and defeat Azula, Zuko's sister, from making their way into Ba Sing Se.
When they finally enter Ba Sing Se Aang and his friends get greeted by Joo Dee, a woman who was assigined to guide them around the city. They attempt to tell her about the war and that they need to see the Earth King, but she simply ignores them, until they arrive at they're house, where she tells them that they meeting with the king is eing processed and will be put through in 6-8 weeks.
When the Gaang gain entry to the Earth King's pet bear, Bosco's birthday party, they are taken away by the Dai Li. There they're leader, Long Feng, threatens them, and they are taken out, by a woman claiming to be Joo De too.
The Gaang spend most of this time looking for Appa, and Aang and Katara find a printer. They put up posters around the city, and when the old Joo Dee shows up to tell them they're unable to post posters around the city, Aang shouts at her. The Gaang are then approached by Jet, claiming to know where Appa is.
After Smellerbee and Longshot see Jet, they all realise that he's been brainwashed. They manage to figure out, with the help of Katara's healing, that something's going on in Lake Laogai. They go to visit there, and they all take on the Dai Li, and in the end, they find Appa.
Next, the Gaang go to tell the Earth King about the war and conspiracy, and eventually, Long Feng is arrested. In the final battle in the catacombs of Old Ba Sing Se, it is thought that Aang is killed while in the Avatar State, but luckily, is saved by being healed by Katara with the water from the Spirit Oasis.
Book Three: Fire
At the beginning, Aang finds himself on a Fire Nation ship which turns out to be controlled By the gang. Pipsqueak, the Duke, and Hakoda and other waterbenders were also on board.
Later on when it's just the gang they are in a forest. An old woman named Hama lets them stay at her house after telling them of a spirit that was taking people. When Hama wasn't home, they went snooping through the house. Toph metalbended a locked door open they find a locked chest. After they try to open it Hama appears and opens it for them. She reveals it to be a comb from the Southern Water Tribe. When Katara is training with Hama, Toph Sokka and Aang go to the hill wheree Toph heard screams. They find people in a cave, locked in chains. They find out that the spirit is actually Hama. Sokka and Aang go after hama while Toph unlocks the people. When they arrive Hama bloodbends them to attack Katara. When Katara attaches Aang and Sokka on different trees with ice, Hama breaks them free with them heading toward each other and Sokkas sword heading at Aang. Katara stops them just in time and bloodbends Hama into the defeat. When Hama is arrested she says her work is done by teaching Katara bloodbending. Katara then breaks down into tears and Aang and Sokka run to comfort her.
The gang decide to rest for awhile. When it is mentioned that there are only for days before the Invasion of the Fire Nation Aang starts to stress out. One night he has a nightmare when he comfronts Firelord Ozai but he forgets his pants. The next night he has his pants in the nightmare but he has to take a math test. Katara, Sokka, and Toph try to help him out. Katara tries to help Aang by doing yoga in steam but fails.
Next Sokka tries to talk to Aang about his feeling about the Invasion. This doesn't work and Sokka suggest to scream in a pillow, which is a koala sheep. This fails to and Toph is next. Toph tries to help Aang by laying him on earth shaped logs. She then gives him a brutal massage but can't take the pain. She then suggest acupuncture with a boarcupine but Aang runs away. After the three's failed attempts Aang decides not to sleep. Aang is now having continuous daydreams like kissing Katara and seeing Momo and Appa fight like samurais.
Aang now exhausted wanders across a bed made of wool. He thinks its another daydream but Katara, Sokka, and Toph show up and tell him its not. They used the wool from the koala-sheep to make it. Aang tells them he's not ready but they insist on sleeping on the bed. Aang falls asleep and has a dream where Firelord Ozai forgot his pants instead.
The morning of the Black Sun their friends and allies come. The Mechanist from the Northern Air Temple has created a new glider for Aang that comes with a snack compartment! When it's time for Sokka to tell the plan he gets extremely nervous. His father takes his place and gets everybody excited. Sokka tells Aang that that was his time to prove himself Aang reasures him that his time will be on the battlefield. To get ready for the battle Aang shaves his head showing his arrow again. Sadly the invasion failed and the elders who were part of the invasion stayed behind while the children went with Aang and the rest of the gang to the western air temple. When they arrived there so did Zuko wanting to join them and be aang's fire instructor to teach him fire bending. Aang and the rest of them struggled to accept him because of their past confrentations with him but shortly after accepted him into the group. Then came the final events, Firelord Ozai had decided to leave the fire nation to azula and for him to rule the world calling him the phoenix king. Aang had consistantly trained for this day so he went after the firelord on the day the of Sozin's Comet and uses it's powers to try to finish the war, But Aang comes face to face with Ozai and defeats him once and for all by bending not the elements but the energy within him. And just when that fight was going on Katara had defeated Azula. While a group of elders called the Order of the White Lotus reclaims Ba Sing Se. At the conclusion of the series, Zuko becomes the new Firelord and him and Aang end up being friends. Together, they vow to restore peace throughout the world which had been suffering so long.
After the Series
Avatar Aang and his friends would go on to do great things during their lifetimes, Aang and Firelord Zuko would use the Fire Nation colonies as a basis for forming Republic City where people of all nations, benders and non benders could cooperate and thrive as a symbol of peace. Aang himself would establish Air Temple Island in the bay as a new Air Sanctuary and a place for his family. Aang and Katara would marry and have 3 children together, Kya (a female waterbender named after Katara's mother), Bumi (a non bender named after Aang's good friend and King of Omashu), and Tenzin (Aang's youngest son and only airbender). Aang served the city until his death at the age of 66, a fairly early death compared to some other Avatar's lifespans, like Avatar Kyoshi. Aang's death is said to have been caused by his continuous use of the Avatar State for 100 years, which severely depleted his chi.. The next Avatar to be born is a female named Korra in the Southern Water Tribe. She has finally unlocked her Airbending and spiritual blocks after having her other three bending abilities removed by Amon. These abilities were restored by Aang.
Aang is naturally an Airbender, and became a master at a very young age. At a young age he created his own Airbending move called the Air Scooter, which allows him to travel at high speeds. Aang is not only an Airbender, but the Avatar, a bender with the ability to master all four elements, and the bridge between the physical world and the spririt world.
Aang most commonly wears his traditional monk robes. He has tatoos all around his body covering his arms, legs, back, and head. While secretly living in the fire nation he was disguised in a fire nation student's uniform including a headband to cover up his arrow. He carries around a staff which increases his control and precision over air while bending. Lastly, Aang travels with a Bison whistle used to call over Appa, which he can hear from surprisingly far distances.
As an airbender, Aang has shown mastery in his primary and native bending skill. He has shown the capability to create domes of compacted air to defend against arrows or the ability to run "as fast as the winds." Throughout the series, his mastery has become more evident when he has shown himself capable of fighting master benders of other arts (such as Azula) using his Airbending most of the time. In season 3, he's shown himself capable of making small tornadoes/cyclones, or sending out a gust of air from his lungs similar to Avatar Roku. Although Airbending has no sub-art, Aang has shown himself to capable of increasing the pitch of his bison whistle while looking for Appa, to the point where animals all over Ba Sing Se could hear it.
When he enters the avatar state, he can create a dome of air in which he may fly around in. The dome is powerful enough to withstand high-speed impacts into columns of solid rock or into the ground ( to the point where he creates a crater) and can withstand the flames generated by Ozai while he was enhanced by Sozin's Comet. He can also create winds that can erode solid rock.
Waterbending was the second art Aang learned to use and mastered. As the Avatar, he's a natural when it comes to Waterbending. When he first started. Katara taught him a move that took her a few months, but only took him a few seconds. Not to mention his was bigger and better. Throughout the series, we see he's an excellent Waterbender, capable of bending entire streams or creating shields of ice. He has shown himself to capable of creating a huge wave that sends him from the middle of the ocean to an extinct volcano (with help from Yue, the moon spirit, but he maintains the huge wave himself) or using ice as stepping stones. In his regular sate, he is a Waterbending master, yet Katara is more prone to using her skills to their fullest extent since it's her only element. She eventually becomes Aang's teacher again (after she's reached the status of master Waterbender) and learns moves such as Bloodbending which Aang has yet to show knowledge of.
When in the Avatar State, however, Aang is the most powerful Waterbender. He has shown himself capable of compressing water and using it to extinguish flames generated by Ozai during Sozin's Comet. Possibly the greatest technique of Waterbender ever shown in the series was during the Siege of the North, when the moon spirit was killed by Zhao. Aang enters the Avatar State and fuses with the ocean spirit. In turn, he becomes a giant fish creature made of blue water, with Aang in the center, controlling the monster through Waterbending. In this form, he takes on a massive army of fire navy ships, with no hassle, and destroys them all. In this form, he was capable of bending massive amounts of water at one time.
Earthbending was the last art Aang learned, but the third he mastered. He's shown himself to have trouble with it as it is his natural opposite element. Whereas Airbending is about evading and finding a different method to things,Earthbending is about being stable and facing things head-on. Despite this, he shown a great proficiency in the art. Being trained by Toph, one of the greatest Earthbenders in the series, helps contribute to this. While Earthbending, he showed himself capable of creating slabs of rocks for cover from attacks. As the series progresses, Earthbending becomes one of his most used elements. He can use it to create an armor of rock to cover his entire body or just his hand, crash through rock columns by Earthbending (while he was fighting Combustion Man), and sense things through the vibration of the Earth just as Toph can. While also airbending, he was capable of creating a zoo made of earth, with very fine details in it. However, he hasn't shown himself to be able to Metalbend.
While in the Avatar State, he showed himself of moving rocks from distance while being in the air, without having to be connected to the ground. When he was fighting Ozai, he compacted giant clumps of rock into smaller pieces, which he could break apart and fire like bullets, which had enough destructive force to destroy several rock columns, despite their size.
Firebending is the third Aang learns, but the only one he didn't have enough time to master. He first learned firebending from Jeong Jeong, as he thought it to be the only time he could learn it. Jeong Jeong wasn't too keen on him not mastering Waterbending yet or learning Earthbending, but Avatar Roku persuaded him into teaching Aang. Aang was a little too anxious and excited about Firebending when finally was capable of creating a flame and controlling it. From this, he decided to send out a huge burst of flame which hit Katara burning her hands (thankfully, she was able to learn how to heal using Waterbending in this very same episode.) After this, Aang vowed to never use Firebending again.
After a talk with Guru Pathik, Aang realized as the avatar, he must learn Firebending. When Zuko joins his group and decides to teach Aang Firebending, they both go the ancient Sun Warrior's ruins to try and learn Firebending from the original source. They learn from the original source, two dragons, that firebending isn't about using hate and anger to overpower enemies. From this, they also learn the dancing dragon, in which they learn a technical series of dance moves that help the user fight around the enemies' attacks. It seems to incorporate some Airbending philosophies.
During his fight with Ozai during Sozin's comet, he was capable of creating giant streams of fire using jabs and kicks. When he entered the Avatar State, he's shown himself capable of bending lava, and creating great streams of fire from each limb and his mouth.
An art long forgotten and taught to Aang by a giant Lion turtle. Before the Avatar came to be, people didn't bend the elements, but the energy within themselves. As of now only the Avatar can perform such an art, and few have learned it, while fewer have even used it. While energy bending, the Avatar may take one's bending (he has also been shown to restore bending as seen in the Legend of Korra episode, "Endgame.".) The user must have a stronger will than the one it's being used on, or else they will become corrupted with the other's energy and be destroyed. While Energybending, the user wants to have the dominant will so their energy will become dominant and fulfill the user's request.
Throughtout the seasons, Aang has managed to master Waterbending and Earthbending, and is beginning to learn Firebending.
Aang has the ability to access the Avatar State, a state which he enters when under great pressure. In this state, his eyes and tatoos glow, and the knowledge of all past Avatars are channeled through him, allowing him to access amazing power through having the ability to bend every element because of his past lives knowledge.
For more information on Air, Water, Earth and Firebending, please visit the Benders page.
Aang's greatest strength and greatest weakness is the ability to go into the Avatar State. In the Avatar State Aang is in perfect mastery over the elements but if he is killed while in the Avatar State, the Avatar cycle ends.