February marks the 15th anniversary of the premiere of Avatar: The Last Airbender, a show that changed the direction of children's cartoons.

As with most revolutionary programs, it can be difficult to remember the early days before Avatar. Up until 2005, the overarching trend for animated series targeted at children was that they were light entertainment or background filler. Certainly, there were exceptions, like the critically acclaimed Batman: The Animated Series, which often elevated its material beyond the vapidity the medium was usually relegated to. But more often than not, in the days before Avatar, there was a hard division between the animated programming targeted at children and the ones targeted at adults.

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Avatar: The Last Airbender

Cartoons for adults were certainly nothing new. The SimpsonsFuturama and Family Guy all proved that there was a reliable audience of adults who enjoy animation, but they also catered toward more mature viewers. This trend in animation operated on a binary, where shows marketed themselves either toward children or toward adults without balancing both qualities. Only the Avatar, master of all four elements, could restore balance to the world.

Avatar's stroke of genius came in crafting a show that both children and adults could enjoy, in a way that made the show feel as though it was made for them individually despite being made for both groups. Themes such as responsibility, pacifism, industrialization, tyranny and self-discovery were evident in every episode of Avatar, and winding it all together was exciting action in a fantastically imaginative world anyone -- regardless of age -- could lose themselves in.

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It's easy to take so much of what Avatar did for granted in a world where similarly ambitious animated projects are about. Phineas & Ferb, Adventure Time and Steven Universe all owe many of their strongest elements to Avatar for making the unity between younger and older animation so successful. Each of those shows brings a different and unique storytelling experience to the table. But what exactly was it about Avatar that made it feel so unique?

Part of the show's success came in the richly detailed worldbuilding. The introduction to Avatar deftly established a storied world rife with political tension, war, tradition and magic. Although Aang began the show as a fun-loving boy unprepared to accept responsibility, the tone and themes of the show grew more complex and mature as the titular character grew along with the audience. All the while, it never quite lost that same spirit of fun. Aang maintains his childlike wonder from Season 1 when he rides a giant koi fish all the way to Season 3 when he Footlooses a Fire Nation town into a dance party.

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Of course, part of what made the world of Avatar feel so different was not just its more fantastical elements, but also its dedication toward diversity that increasingly became the standard rather than a deviation from the norm. By normalizing things like an Eastern-influenced setting, culture, clothing and spirituality, the show offered children and adults alike insight into differing perspectives that they weren't necessarily familiar with.

The same dedication was mirrored in the show's commitment toward presenting empowered female characters. Katara started the first season as a timid yet strong-willed girl, but by the end of it grew into a capable and assertive master, literally challenging the patriarchal structure of the Northern Water Tribe. Season 2 then saw the introduction of Toph (originally conceived by the creators as a male character) and Azula, both of whom proved to be some of the deadliest and most powerful characters the show had to offer.

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Without any sense of pandering or cheap pacification, the show presented a full spectrum of personalities far beyond the limited scope of most kid's cartoons at the time. That same spirit continues in other aspects of the franchise, making the nonwhite Korra the star of the sequel series The Legend of Korra and the bisexual Kyoshi the star of the first novel, Rise of Kyoshi. Keeping a franchise alive for 15 years is tough enough, but maintaining a spirit of progressivism that never grows outdated is a testament to just how far ahead of its time Avatar was.

Many of the creators involved in Avatar even went on to blaze the trail for other shows capably promoting diversity in their casts. Showrunner Aaron Ehasz's The Dragon Prince prominently features nontraditional family structures and nonwhite characters, while the original season's director, Dave Filoni, went on to create Star Wars: The Clone Wars and Star Wars: Rebels. When it comes to the future of Avatar itself, though, returning to the original series will be the next big step for the franchise. With Netflix developing an adaptation of The Last Airbender, it will be exciting to see what the show that revolutionized animation can do in the world of live-action.

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