A day in the life of the Linux kernel starts just a few microseconds after midnight. The kernel, a thin layer of software that provides a consistent interface between the hardware of a computer and the systems library, is hard at work at stock exchanges in the US, where it has almost completely supplanted other alternatives.

Because the kernel’s licence encourages copying and modifying, the financial industry has done just that, tweaking it to perform at the utmost speed without breaking. Linux handles billions of transactions every second, passing information between processes, and managing multitasking environments for the world’s financial markets. Linux is the most portable piece of software in the world.