What are Coremods (Minecraft)?

Question is in the title.

Mods needed by other mods to work.

Usually these are linked on the main mod page.

It is the basic structure of the mods that you need that means that a mod that needs a core mod works on the code of the core and without the foundation your mod can't work mostly there are mods that are very complex but to be on the safe side you can see it

ps: with download link.

Just what I wrote in three times as complicated.

But in more detail, but the same input is true.