Here we will learn the basic concepts of the plugin that your players will have to understand.

Kingdom

A kingdom is a group of people that share the same lands and resources.
Each kingdom has its own resource points, bank, upgrades, ranks, relation attributes and lands.
Kingdoms can create or join nations. They have their own tax equations that can be changed when collecting taxes from the members. If a kingdom doesn't have enough money in the bank to pay server taxes, it'll be disbanded. New kingdom don't need to pay taxes for a few days.
You can rename your kingdom and set a lore for it using /k rename and /k rename commands. This will be displayed when a player moves to your land as a title, which is called land indicators. Kingdom name and lore options can be modified in config.yml kingdom-name and kingdom-lore sections.

Land

Basically a chunk is a land. Lands can be claimed by kingdoms to protect their chests, place turrets and structures. You can claim a land using the /k claim command. There are other advanced claiming commands that make this process way easier. The easiest way is to claim chunks from the map /k map
Note: You might come across the term claim somewhere. This simply refers to a land that is claimed. Not all lands are claimed. A land is technically any chunk that contains any sort of kingdom data.

Pacifism & Shields

Kingdoms can choose to be pacifist or not, they're not pacifist by default. A pacifist kingdom cannot invade and cannot be invaded.
Kingdoms cannot go in pacifist mode after a certain amount of time after their last invasion.
Whether you're pacifist or not, you can also purchase shields from the nexus settings to stop kingdoms from invading you. New purchased shields will add to your kingdom time shield if any is active.
Shields costs and duration can be modified from guis -> structures -> nexus -> settings -> shields
It's preferred to remove the pacifism (by removing the option for the GUI) and use shields only. This will encourage and motivate player to earn more resource points to keep their kingdom safe. New kingdoms will get a free shield for few days to prepare.

Resource Points

Resource points are kingdoms main currency. You can use them to buy turrets, structures, shields, ammos and upgrades. They can be produced from the Resource Points Converter in the kingdom's Nexus. Unlike the old Kingdoms, if you close the GUI after putting items in the GUI, it'll return the items without converting anything. It works the same way if you use the Back button. You have to click Apply.
Some items are blacklisted from converting to avoid mistakes and cheating. They're returned to the player's inventory.

You can get one resource point for every 5 non-special items you put in the converter. Special items such as emeralds, diamonds, gold, irons and etc... give a specific amount of resource points per item.

All of these behaviours can be changed in config.yml -> resource-points section.

Other than resource points, kingdoms uses the money economy system (if available) for kingdom/nation creation, taxes, claiming a land etc. This economy system comes from any plugin that supports Vault.
Plugins like EssentialsX or CMI (CMI provides their own Vault version) support Vault.

Powerups

Powerups are common boosters (such as damage boost, damage reduction, arrow damage boost and regeneration boost) that only work when you're standing in your land. It doesn't matter where your target is standing or where your arrow landed.
Regeneration boost only works for eating regeneration, not any other regeneration such as the natural regeneration.

Might

Kingdom and nation ranks are determined by their might (/k top and /k nation top). Might equations can be found in config.yml -> top-kingdoms or top-nations -> might
The default equation has resource points and the member count as its main factors. It's recommended to use + operator to keep this number low.
When taxes are being collected (during the daily-checks-interval), the top 10 kingdoms and nations will be rewarded with money and resource points. You can change the top and reward amounts in config.yml -> top-kingdoms or top-nations -> rewards

Nexus

A nexus block is a structure that is the most important thing in your kingdom. These are some kind of "virtual" structures, meaning they don't have an item, they won't drop an item when broken, can be placed as many times as you want using /k nexus command and they will be removed automatically once a land is unclaimed or invaded.
Almost everything in your kingdom can be accessed and modified from your nexus such as ranks, upgrades, turret and structure shops, member list and etc...
If another non-ally kingdom mines your nexus, it'll take a certain amount of resource points from your kingdom, so it's important to cover your nexus properly. Nexus settings can be changed from config.yml -> nexus. There are also some options in invasions.yml that can change the invasion behaviour after a nexus land is invaded.

Relations

In Kingdoms you can have the following relationship with another kingdom:

• Self: You won't see this in-game. It's for config and API purposes. It's basically indicating that the target kingdom is yours.
• Neutral: You have no special relationship with this kingdom, or the target land or player doesn't belong to a kingdom.
• Nation: You're in the same nation with this kingdom without an individual relationship.
• Ally: You're allies with this kingdom.
• Enemy: You're enemies with this kingdom.

If you're in the same nation with a kingdom, you can still have an individual relationship with them. You can change this behaviour by changing prioritize-kingdom-relations and allow-relations-between-nation-kingdoms in relations.yml

Kingdoms can also have custom relation attributes. You can manage your kingdom's relation attribute by going to your nexus settings.
One important thing to know is that the relation settings only apply to the kingdom itself, it won't change for other kingdoms that have a relationship with the kingdom. For example if you have ceasefire attribute off for allies, but your allies have it on, you can attack any of your ally members, but they cannot fight back until they disable that attribute for allies as well.

Ranks

Kingdom rank settings can be changed in ranks.yml file. These ranks are customizable by default. Each rank have its own unique node and priority, but other options such as the name, color, symbol, material and max claims can be the same. Nations are the same and use the same settings from ranks.yml All these options except the material can be accessed as a placeholder for both kingdoms and nations.
Other than your own kingdom, rank permissions are also used after checking a relation attribute between two kingdoms. If the relation attribute is positive, it'll check the player's permission for some cases. For example, when placing blocks in another kingdom's lands, first it'll check if the kingdom relation allows such a thing between these two specific kingdoms, then if passed, it'll check if the player can place blocks with the rank they have.

• Node: The rank node is used to refer to an unique rank while managing a specific rank in-game or from the code.
  This name must be unique per kingdom, without spaces or special characters (even though it's possible)
• Priority: The highest rank (called king by default) has a priority of 0 and the lowest rank (called member by default) has a priority the same as the size of the ranks minus one. Although it's possible to do this from the API, rank priorities cannot be less than 0 or higher than the member rank priority.
• Material: This is only used to show the rank in the GUI.

Nations

A nation is a group of kingdoms that share the same relation attributes. They're made as a replacement for kingdom relations, however having a relation with another kingdom outside of the nation is still possible. Nations are quite similar to kingdoms except they don't have any upgrades. The kingdom that created the nation, is called the capital. The king of the capital is the king of the nation.
Nation taxes are collected after player taxes are collected for each kingdom. If a nation cannot pay the taxes after it collected the taxes from each kingdom, it'll be disbanded.
Nations use the same options as kingdoms option for almost 70% of the settings in configs.

Benefits of joining a nation:

• Increased max lands.
• When a kingdom that is in a nation gets invaded, the capital kingdom champion will spawn.
• Get notified when a kingdom that is a member of your nation gets invaded.
• Nation shield can be used for all the kingdoms.
• Nation Chat
• Nation Ranks
• Nation Zones

Disadvantages

• If your nation doesn't have a shield, players can invade any of the member kingdoms even if they have an active shield individually.
• Nation pacifism state is forced for kingdoms.
• When the capital champion is weaker than your kingdom.

Nation Zones

Nation zones are the lands around the capital kingdom's land. The default radius is 1, meaning 3x3 chunks around each land that belongs to the capital kingdom. These zones are basically like Powercell structure, but they cannot be invaded, claimed or used for building by another kingdom that is not in the nation same nation as the capital kingdom. In order to access these lands, you have the invade all the claimed nation lands around the land (3x3). Nation zones are not shown in the map. If the capital claims a land next to a claimed land from another kingdom that is not in the nation, the claimed land will not be affected by nation zones if it's inside of the 3x3 zone range.

Taxes

Taxes are collected every 24hrs (real world time) by default from kingdom/nation bank. This can be changed in config.yml -> daily-checks-interval You cannot use resource points as the tax since players can't save resource points. New kingdoms, members and nations are excluded from paying taxes for the first few days by default. This can be changed in config.yml -> tax -> kingdom/nation -> age Kingdoms and nations can also set their own tax equation from their nexus settings.
You can also perform a manual daily check using /k admin dailycheck command.
This is a tree showing how the overall tax collection process works. Note that the age restrictions are not shown in this tree. Yes, the design isn't really appealing...