Reborn Core Mod [1.18.2, 1.17.1] has included a set of code and generic API for mods of the author in Minecraft (it is compulsory to install for using).
A supporting mod, RebornCore-Mod will not have any effect when installing independently in Minecraft. Instead of that, it will help other mods to run. The mods that RebornCore-Mod has supported frequently used in a general set of code in structure. And then, it will reduce the size of the file and save time, as well as optimize the system. Therefore, the author has combined this code set into RebornCore-Mod. You should notice that if not installing this mod before using basic mods, it will cause some errors in the game and you cannot load until logging into the main menu!
Some popular mods use this core: TechReborn Mod, Quantum Storage, Fluxed Redstone, Hardcore Map Reset, etc.
How to Install Reborn Core Mod 1.17.1, 1.16.5 for Minecraft