Why Most Operating Systems Are Written in C

Most operating systems are written in C because the language is simple, portable, and close to hardware.

C’s concise syntax is captured in K&R’s classic book, and its minimal runtime allows it to be ported to many CPU architectures.

When designing a CPU, developers often provide a C compiler first, enabling them to write system software without a heavy runtime like Java or C#.

C gives programmers direct control over memory, pointers, and hardware resources, which is essential for tasks such as page‑table creation, DMA control, and memory‑mapped I/O.

Unlike languages that require extensive runtime systems, C programs can run on bare metal, making it ideal for OS kernels.

The OS sits between applications and hardware, so it must manage hardware directly; C’s transparency and lack of hidden abstractions make it suitable for this role.

In summary, C’s independence, low‑level access, and simplicity make it the preferred high‑level language for system programming, though other languages are better suited for application‑level development.