Linux is EVERYWHERE! As few as 5 years ago, if you mentioned Linux at work you were viewed as a radical, which can make it rather hard for someone who is a conservative engineer+MBA who loves Open Source. Things have changed and Linux plus Open Source are now widely-accepted and virtually EVERYWHERE!
A long time ago, in a galaxy far away, there were other operating systems and computers besides the corporate DOS/Windows desktop. Many of us were exposed to them (IBM VM, VAX VMS, UNIX, Xenix, etc.). When we used these systems we realized that computers did not need to crash twice daily and could actually do more than one thing at a time (a world beyond INKEY).
I used IBM VM in college and once I graduated I used a VAX for many years. My first Unix-like O/S experience was with Xenix. We learned Xenix then UNIX, then Linux, starting in the 1980s (sure makes me feel OLD). Back when I started using UNIX/Xenix in the mid-1980s the computers we used cost thousands of dollars and were much faster than PCs. The only thing on PCs at the time was DOS, which despite the name Disk Operating System really is not a true operating system! (You have to do WHAT to read the keyboard and serial port? Inkey? Poll them?)
My copy of Xenix cost about $400. But wait, there's more. To get the compiler, you needed to pay an ADDITIONAL $400. No wonder why SCO wanted to charge EVERY LINUX USER $600! BTW, this $800 DID NOT include Ethernet or any networking other than UUCP. Quite ancient by any modern metric. However, I could make these computers "sing" -- really work and work well, with up times measured in months and years. How many DOS computers ran for a solid year without rebooting in 1990? None that did anything useful....
The first time I saw Linux, a co-worker loaded it on a Dell 486 with 16M of RAM running from a 100M Bernoulli drive. It was slooooowww, but it ran X Windows and had a full development environment. The kernel was Linux 0.99pl13, released in September 1993. It was a Slackware distribution on 20-30 floppies. Red Hat and Google were still way in the future.
Linux got NO respect. A few years later, I was at Comdex and chatted with a suit getting out of the elevator. I commented on how surprised I was at the lack of Linux. His response was very telling for the times: "No self-respecting business will bet their operations on an operating system built by hackers".
Fast forward to the 2000's. A few companies got their start with Linux including Red Hat (founded in 1994) and Google (1997-1998). Over 10 years ago, a few companies re-tooled themselves around Linux including IBM and Oracle. Linux and open source became an "enabling technology".
Where is that company that based their operations around Linux, Gaggle or Goggles, or Google or something? Google has a small $360B market cap (2/2015), worth more than Microsoft's $340B (2/2015) [when I first wrote this draft it was the other way around]. Most of our cell phones run Linux (Android, Firefox OS, Ubuntu Phone, etc.). The hottest selling laptops (Chromebooks) and tablets run Linux (GalaxyTab, Amazon Fire). Smart TVs and BluRay players all have Linux under the hood. Media share devices like Google Chromcast and the Amazon Fire TV are Linux. Most of the large financial trading systems are Linux (Microsoft tried and failed). Most of the largest web sites on the Internet run some version of Linux. About 95% of the top 500 supercomputers run Linux. Linux runs on Android phones, smart watches, and even $20 Raspberry Pi boards. A co-worker even has a high-end digital SLR camera running Linux.
If you go in Best Buy you won't see Linux advertised, but nearly all those smart devices have Linux under the hood.
Back in the 1990s governments were shy about that "Operating System Built by Hackers". Today the US Navy's newest destroyer, USS Zumwalt is a floating Linux data center. The Army just released a massive security application as open source. The NSA created SELinux to better secure Linux. A quick search of job sites show hundreds of Linux jobs supporting governments all over the world.
Linux is now everywhere and is expanding into new markets daily.
What are you doing with Linux today?
BTW, why am I still getting questions about who uses Linux????