I apologize if this is a subjective or repeated question. It's sort of awkward to search for, so I wasn't sure what terms to include.

What I'd like to know is what the basic foundation tools/functions are in C when you don't include standard libraries like stdio and stdlib.

What could I do if there's no printf(), fopen(), etc?

Also, are those libraries technically part of the "C" language, or are they just very useful and effectively essential libraries?