Birthdays are always important, and birthdays that end in zero are especially significant. 30 years of Linux? Seriously? I guess we always knew that Linux was cool, but those of us who were around the water cooler in the early 90s when the first mentions of a new free operating system began to trickle out to Usenet groups never would have guessed that Linux would ever get as big as it is today, running on web servers and washing machines, desktops, cell phones, Mars rovers, and supercomputers around the world.

When we were considering a topic for the 30th birthday of Linux, it soon became clear that the only real way to celebrate was to write about Linux itself – not the agglomeration of software we know as a Linux distro, but the real Linux – the beating heart in the center of it all: the Linux kernel.

When it comes to birthdays, I should add: We ship this magazine all around the world, and it arrives on different shores on different dates over a range of almost two months. So I'm not sure when this issue will actually reach you, but the date we are commemorating is August 25, 1991, when a Finnish college student named Linus Torvalds left a message on the MINIX newsgroup announcing that he was working on a new operating system.

MINIX, which still exists today, is a system created by the famous computer scientist Andrew Tanenbaum that is often used as an educational tool for people to learn about operating systems, so the MINIX community took a special interest in the newly minted Linux. Interestingly, Torvalds and Tanenbaum had a bit of a falling out in those early days over system design: MINIX is a microkernel system, which was thought to be more stable and state of the art, whereas Linux was a monolithic kernel, which looked very retro to the experts. But history has vindicated Linus for this choice: Linux systems now run on most of the biggest and most powerful computers in the world. (In case you are wondering, Linus has since patched up his differences with Tanenbaum, who wrote the book on operating systems that Linus referred to when be built Linux and therefore was something of a mentor.)

This magazine is about diving down deeper into the Linux computing environment, and we continue that mission with this month's cover story. We show you how to tweak the kernel to improve overall performance and response time. We also take you inside the kernel for a close look at how buffer overflow attacks actually work – and why you should install those system updates as soon as you can. We show you how to compile the kernel yourself, and we ask senior kernel manager and Linux Foundation fellow Greg Kroah-Hartman how to get started working with the kernel community.

If you're new to the kernel, or even if you've been around for a while, you'll find something useful in this month's issue. Happy birthday to Linux! Turn the page, and pass the cake.