C has come to practically define the entire computing landscape at the moment.
C is the de facto standard for not just writing Operating Systems and kernels, but also how APIs are presented to the developer and user.
Languages like Java for example, generally you’ll write 99% of code in Java, but you also get the opportunity to call C code too, via JNI. Just about any serious language/runtime lets you do this. So if we can consider languages like cars, i.e. Java is a Toyota, Python is a Honda, JavaScript is a PT Cruiser etc. then C isn’t just a language, it’s the roads.
There are many different Operating Systems, but one thing unites practically all of them, and that is C, not just in using it, but using how C presents calling conventions to just about everything else. Even esoteric niche OS like Inferno, you’ll write all software in Limbo and run on the dis runtime, but if you want to drill down to the hardware, or extend the OS, you’re into C.
Operating Systems not written at least partially in C are a rounding error, it’s a tiny fraction of 1%.
At a systems or hardware level C doesn’t just dominate, it really sets the rules for the whole game.
A lot of programmers (especially beginners) don’t really notice C, and don’t really notice where it’s used, but I compare that to this:
How often do you stop to notice the ground under your feet?
