In this world named Ostaria there are many different species, but all these species can be put in either of two categories: Elementals and Elemental Beasts

Elementals are us, we have a Core that let's us manipulate the Element we are attuned to, letting a Fire Elemental control flames or a Water Elemental separate water from mud, there's many things that separate an Elemental from one another, for example an Elemental can have more than just a single element inside of them, these Bi-Elementals are exceedingly rare and take on concepts rather than a full Element, like Mist and Magma, then there's the Thri-Elementals, they take the form of a more refined concept, like for example, A Storm Elemental has the Water, Wind and Lightning element.

Even inside a single element there's mutiple concepts, for Earth there is Sand, Stone and Gem among others, these vary wildly yet they share the category of "Earth", This is one of the more varied, having multiple sub-categories for each type of stone, Gem and even sand.

Fire doesn't have any sub-categories, the difference between Fire Elementals is based around how hot their fire burns, going from Red all the way to Purple.

Wind doesn't have any sub-categories, just like Fire the difference is more based around what their Wind carries, from dust, sand, even water and ice, to glass.

Water is the second most varied, with ice, water, and vapor, Water is also very intertwined with Wind, as Bi-Elementals with these two elements are of the most common.

Metal is often considered its own category rather than a Sub-category of Earth, as it has a lot of subcategories by itself, going from the humble Coppper to Titanium!

Lightning is one of the more mysterious elements, rather than sub-categories it has applications that any Lightning Elemental can do, like: Plasma, supersonic waves, and a Lightning Elemental can function as a signal jammer, relay point or a fully functional radio station by themselves with very little equipment, and that's just on the technology side, as in legends it's said to even hurt ghosts and other apparitions, though this remains unproven.

Plant Elementals are similar to Lightning Elementals in the regards of being able to do anything without the need of sub-categories, but rather than aiding on the progress of science Plant Elementals focus on the body, being the defacto healers, this doesn't mean Elementals like Fire or Wind can't heal, but it's rare for them to possess the "Life Force" concept that all Plant Elementals possess, even though the term "Life Force" is outdated, it is still useful as its a simple way to explain the very mysterious energy that let's Plant Elementals do their wonders.

There's also other 2 "Elements" that aren't really Elements, these are Light and Dark, these elements are considered separate from the others as they affect a person no matter the Element they posses, for example a Fire Elemental that is affected by the Light Element can do the simple parlor trick of turning their fire invisible or turn it into an extremely hot Plasma that has physical form, with the Dark element is something more simple, if we go with the same Fire Elemental Example it lets them do the same thing, use the Dark element in their fire and consume the Light Element, thus turning them invisible in the shadows, this can also go as far as making the mythical BlackFire, an all consuming fire only spoken of in legends.

Elemental Beasts:

Contrary to popular belief, Elemental Beasts are not Elementals whose core became the inverse for some curse or voodoo nonsense,

Elemental Beasts are all around us, from the ants that someone inadvertently squashes in their way to work to the mighty True Dragons that soar the skies and sow destruction, they have the same Core, and this Core is the opposite to ours, instead of absorbing, nurturing and refining the energy of our chosen element the core of Elemental Beasts only consume, like a hungry void that yearns to consume the world whole, this is why Elemental Beasts are so aggressive, they are haunted by an endless hunger that cannot be quenched, this is also why they hunt us, we are full of the Elemental Energy they want, so they will stop at nothing to get it.

Thankfully, we are not defenseless, as unlike our own Cores, theirs do not dissapear after death and continuously consume the energy around them to maintain their physical form, this let's us use them as batteries to fuel our mighty machines, like the planes that soar the sky and the boats that sail the sea, their bodies are also a treasure trove of materials to make weapons, armors and many other trinkets as Elemental Beasts continously saturate them to make them stronger, they may hunt us, but we also hunt them.

Excerpt from "Our Wonderful World" Written by "Wallace V. Willoughby"