From the introduction:
Technology and Bending are two very important powers in Valdar and are equally common and go hand in hand. Most technology is powered, inspired, and created by bending. From the powerful Goblin warships of the sea and sky, to the Yssar warsubs, to the Klimshar and Alder airships that fly over the world for years on end. Technology is everywhere just as bending is. There are many technologies in Valdar, but the most significant (and the only ones discussed in depth here) are vehicles of the land, air and sea and ballistics and the chemicals that make those possible.
User summary:
Valdar - World of Elemental Leylines presents a fairly standard fantasy-fantasy genre setting infused with "bending" magical abilities - a concept borrowed from Avatar: The Last Airbender.