The C language is still prominent in the industrial embedded world, where “IoT” often refers to platforms much more limited than a Raspberry Pi. Often having to deal with such environments, we wrote the following informal explainer about C for internal company needs, and thought it could be of interest for more readers. This is basic material, mixing C and operating systems knowledge, aimed at readers with no or limited understanding of how you go from C source code to an executable. We could expand on many points, but for now we just share this meandering overview.