There are ten 'realms' of cultivation in the world of Reine. The first follows it's own rules, as detailed here:

Tier 1 - Mortal Realm

The Mortal Realm is then split into 6 stages, each stage being a different part of the body that a cultivator must reinforce and remove impurities from in order to progress. If someone is stupid enough to follow a different order than what is detailed here, they are likely to literally rip themselves apart. After all, having super strong muscles is useless if every time you use them you pulverise your organs and bones. The stages are listed here:

Stage 1 - Internal Organs (not including brain, but this will be explained early on in the novel)

Stage 2 - Bones

Stage 3 - Brain

Stage 4 - Blood vessels

Stage 5 - Skin

Stage 6 - Muscles

(There is also a seventh stage, but this is only accessible to our MC Evie, and only because of her SYSTEM. This stage is: Stage 7 - Keratin and immensely strengthens her hair and nails, to the point that it takes someone of at least 2 stages higher in cultivation than her to cut them unless she does it herself, as she can coat her clippers/scissors in her own Qi, which allows her to cut them.)

The next eight follow a structured set of rules, that most people know and are treated as common knowledge, even among commoners (almost all non-cultivators are commoners, with very few exceptions). They are:

Tier 2 - Meridian Opening Realm

Tier 3 - Qi Consolidation Realm

Tier 4 - Core Formation Realm

Tier 5 - Core Reinforcement Realm

Tier 6 - Soul Formation Realm

Tier 7 - Nascent Soul Realm

Tier 8 - Spirit Sea Realm

Tier 9 - Immortal Realm

(To advance into the Immortal Realm, a cultivator must have chosen a Dao that resonates with them and that they have fully comprehended, but this will be explained in the novel well enough that I don't feel the need to give more than a cursory explanation)

Each realm has 4 stages, these are: Low, Mid, High and Peak (our MC Evie has access to a fifth stage, Perfect, but again this is only due to her SYSTEM, and it means that her SYSTEM has measured her cultivation and has deemed it as high as she is literally capable of. The importance of this will be explained later on).

The realms are measured like so:

Low - less than 50% progression

Mid - 51% to 75% progression

High - 76% to 90% progression

Peak - 91% to 99% progression

Perfect (only for Evie) - 100% progression, the utter limit of possibility

Then there is the mythical tenth tier. Whether it even exists is a point of contention for many, although obviously it is a thing otherwise I wouldn't bother mentioning it. Anyway, to explain how it works I'll need to explain progression first.

You see, when cultivating, you can technically advance to the next realm at any time. However, it is impossible to gain a higher percentage of progression than you had in the last realm. For example, if someone was in Qi Consolidation Realm and had achieved 88% progression (High Stage) then they could advance to Core Formation Realm at any time, and they would be in a strong position too. However, once they did that, they would never be able to attain even 89% progression - Peak Stage would be forever barred for them. The only way to overcome this would be for them to cripple their cultivation completely, heal it, somehow not die in horrible agony, and start again from scratch. You can see why this isn't a particularly desirable outcome.

Another thing to note is that the lower your progression is when you advance to the next realm, the harder it is to attain the highest you now can. Therefore, excluding the initial difficulty, achieving 100% 4 times is actually easier than achieving, say, 95% the same amount of times in succession. There is also a dependency on the cultivation technique(s) that you are using but that will be explained in a different auxiliary chapter.

Anyway, back to what I was saying about the tenth tier, or as it has been dubbed: God Realm.

How powerful you are as a god is dependant on how far your progression was into Immortal Realm when they Ascended. Also, the Dao that they had comprehended to reach Immortal Realm becomes their Domain, which they have complete and utter control over. There can be more than one god with the same domain, but the god with the higher progression when they ascended will always be more powerful, though not necessarily more skilled. What is special about this realm is that, as opposed to the Immortal Realm, which grants a kind of pseudo-immortality with which you truly do not age, is that cultivators in the God Realm can ONLY be killed by another god or by a weapon thoroughly infused with divine essence (something only gods can use). Therefore, cultivators who have 'Ascended' are as close to true immortality as one can be (this does not include the One Above All, but she isn't really a character yet and won't be until at least the third book).

ALSO, and this is important, for cultivators of any of the first 9 tiers, be they Mortals or Immortals, their children will be born MORTAL and with no cultivation. There are no exceptions. Children of gods, however, are different. If it is a child of a god and a mortal, they are classified as a demigod. This basically just means that they are born at Meridian Opening Realm with 100% progression through the Mortal Realm, which is already an insane head start. Children of two gods, however, are unique. They are born in God Realm and with a Dao that is perfectly suited for them, but most of their power is locked to them until they have it unlocked in a special ceremony called the Celestial Breakthrough, which is done when they reach the age of maturity, because no one wants a bunch of babies with superpowers running around blowing shit up. It is very difficult for gods to procreate, though, and so harming a Celestial (term for natural-born gods who still have their powers locked) is the highest taboo in the entire universe. Gods are more likely to get away with destroying an entire world then harming a Celestial.