The world of Avatar: the Last Airbender and The Legend of Korra has its own magic system, known as bending. The four classic Greek elements of fire, water, wind, and earth can be harnessed with bending, and save the Avatar, a bender can wield only one element. The Earth Kingdom, the world's largest landmass, is home of most of the world's earth benders, and se of their earth bending powers are truly earthshaking.
The earth is solid, ancient, and unyielding, and earth benders have long since incorporated this philosophy into their bending art. These benders, unlike fleet-footed air benders or aggressive fire benders, use a low center of gravity and simple movements to move huge amounts of stone and soil for construction, defense, or even attack. But there is more to the earth than the ground under one's feet.
Badger Moles Invented It
In the Avatar world, each of the four elements had an original bender. The moon bended water, dragons bended fire with their breath, and sky bison bended the very air. Deep below the surface, badger moles bended the earth to create their subterranean tunnels and dens, and humanity soon learned how to do the same. But while some earth benders (such as the fight club ones) have a shallow understanding of earth bending, some benders such as Toph Beifong learned directly from the badger moles and became better benders for it.
Oma and Shu
Toph learned a lot from the badger moles, but history says that the two lovers Oma and Shu first brought earth bending to humanity. According to a tale Katara and Aang learned in Book 2: Earth of The Last Airbender, the two lovers Oma and Shu hailed from rival tribes and learned earth bending from the badger moles so they could secretly meet. After the male lover fell in battle, the woman used her skills to unite the feuding tribes and create the city Omashu, named after her and her fallen lover's honor.
Metal Bending
In a moment of crisis, Toph pioneered a whole new field of bending known as metal bending. By bending the impurities in steel and iron, she could reshape metal with her bare hands (and feet), and soon opened a school to teach this craft to talented earth benders. By Korra's time, metal bending was commonplace, and Republic City was kept safe with squads of metal bender police. And as for Zaofu, the entire city is crafted by and home to many talented earth benders, including Toph's daughter Suyin Beifong and her children.
Lava Bending
While metal bending is a rare and extraordinary use of earth bending, lava bending is a truly exceptional branch of bending. Only two lava benders, Gazan and Bolin, are ever seen performing this art. With it, a lava bender may convert stone into molten lava at will, and control it freely for offense or defense. Fields or streams of lava are often an excellent way to control access to an area, whether to block an attack or cut off an exit. And with enough force, lava bending can topple even the largest structures, such as an Air Nation temple.
Magnetize With the Feet
Ba Sing Se is home to the Dai Li, elite earth benders who silently bend chunks or rock with terrifying skill and discipline. They are even seen standing on the ceiling or running along walls in the city, but how do they do it? Skilled earth benders can magnetize their feet to rocks and soil making it easy to climb a rock wall or cliff. An earth bender always has an exit, it seems.
Creating Buildings With It
In real life and the Avatar world alike, stones and earth make construction possible. Just look at the real-life Egyptian pyramids, or the ziggurats of ancient Mesopotamia. Back in the Avatar universe, the Earth Kingdom is home to cities that would be impossible anywhere else, such as the mountain-city Omashu or the sprawling, walled-off Ba Sing Se. All cities are built on the earth, and if earth is your element, the possibilities are endless.
The Feet Can See
An overlooked fundamental of earth bending is the use of bare feet to sense all vibrations in the ground. With this skill, the blind Toph Beifong could see nearly anything, and her daughter Lin could do much the same. In seconds, Lin could sense the entire layout of an underground Equalist base and find her imprisoned metal bender police there.
It is Based on Spring
In the Avatar universe, each season corresponds with an affinity for one of the four elements. Many fire benders are born in summer, most water benders celebrate their birthday in winter, and air benders are often born in the cool autumn season. That leaves spring for earth benders, and more earth benders are born at that time than any other. It is during spring when the earth is home to reborn life, such as blooming flower fields, trees, and much more. Not to mention how the frosty earth melts when spring arrives.
Sand Bending
This is one diverse bending art, and the sand benders represent yet another variety of earth bending. In the great Si Wong Desert (both Aang and Korra explored it at some point), local earth benders get around on sail gliders by bending the very sand around them. In this way, they loosely mimic air bending as they throw countless sand grains at a glider's sail to make it move. Without this art, the desert might well be impossible to inhabit, but these hardy people found the way. They can even haul away a heavy sky bison this way: in particular, the poor Apa.
Neutral Jing and Patience
Earth bending is by no means a pacifist art, but neither does it subscribe to fire bending's philosophy of aggression and speed. When Aang met King Bumi for the second time, the young Avatar learned that in between positive jing (attack) and negative jing (retreat) lies neutral jing, the core of earth bending. As Bumi put it, "wait, and listen." An earth bender will sense their surroundings like the patient earth itself, and while the earth bender may not strike first, they may very well strike last. Toph certainly does this, and the results speak for themselves. Just ask The Boulder.