On Monday, November 27, 2023 6:03:22 AM MST BoQsc via Digitalmars-d-learn wrote:
> This is pretty basic question.
> If you open [D Library
> Reference](https://dlang.org/phobos/index.html) you are bound to
> see the **Internal API** section in the table of content.
>
> What is the **Internal API** (internal.core, dmd, rt) for and
> when, how and where to use it?
>
> ![](https://i.imgur.com/WyemZsG.png)

They're modules that are supposed to be internal to the implementation. They should not be accessible to anyone outside of those projects. So, it's pretty weird that it's up on the website, but my guess is that someone put it there so that the folks working on the code base could see the rendered ddoc comments for that code. For instance, I could believe that the dmd section there is there just to make it easier for some of the folks working on the compiler to more easily get an overview of the public symbols within those modules. But if you're not contributing to those projects, there really isn't any reason to see those modules.

- Jonathan M Davis