Linux runs around 99% of internet servers. It used by almost every organization because it's extremely reliable, stable and often free.
Linux is now tested in most IT exams from the LPI Essentials to the CompTIA Network+. It's very important to have it featured on your resume. Even if you have only passed the basic exams, it will go a long way when it comes to job interviews and salary levels.
If you want to learn more, you can join this website or our labs-only sister website 101labs.net.