C is a general-purpose, compiled, statically-typed procedural programming language created by Dennis Ritchie at Bell Labs in 1972. It was developed alongside the Unix operating system, and to this day large parts of Unix/Linux, device drivers, embedded systems, and even the runtimes of other languages (Python's CPython, parts of Node.js) are written in C.
#include <stdio.h>
int main(void) {
printf("Hello, world!\n");
return 0;
}
C gives you direct, low-level control over memory and hardware while still being far more readable and portable than assembly language — this combination is why it's often called "portable assembly." It compiles down to fast machine code, has a tiny runtime footprint, and its syntax and core ideas (functions, blocks, operators) directly influenced C++, Java, C#, JavaScript, Rust, and many other languages.
C is standardized by ISO/ANSI, and the language has evolved through several versions: C89/C90, C99, C11, C17, and the latest, C23 (formally published in 2024). This notebook explains core C thoroughly and calls out modern C23 features explicitly where relevant, noting which compiler versions support them.