Cultivation Realms - (Spoilers)

First Realm - Mortal:

Mortals will never be able to surpass the limitation of the mortal body without external help of the energy in the atmosphere, a cultivation technique can assist in this yet some truly gifted or hard-working individuals can push past this and achieve the Mortal Leaving Realm; however, without a cultivation technique they're destined to not make it far on the path of cultivation with effort alone unless they find their own way to circulate the worlds energy in their body and create their own techniques...

Second Realm - Mortal Shedding:

The Second Realm of cultivation is unique, in this realm ones lifespan is increased by 100 Years yet they are still not considered to be true cultivators as they haven't broken through the mortal limitations of the body only having unlocked the ability to store the energy of the word and use it freely, they absorb energy from the atmosphere at an extremely slow pace.

Third Realm - Core Gathering:

The Third Realm is when the cultivator is truly considered to have entered the world of cultivation - their life span being increased by three hundred years, at maximum they can life to 500 Years old and some monsters with stable foundations can live for at most 100 Years longer.

At this realm the mortal body is shed and reinforced by the core the cultivator creates within their body - it becomes the core of their body, if it shatters the cultivator also dies. The body of third realm cultivators is considered to truly have surpassed the limits of the mortal body and has superior reaction speeds to that of a Mortal Leaving Cultivator, mortal weapons cannot even pierce the skin of these cultivators.

Fourth Realm - ???:

No information is currently known other than that it involves building layers on top of the core, protecting the core and compressing it into a pure golden pellet.