On job interviews or contribution queries, many of us have been asked questions like "are you good at Linux?" and "do you know Linux?"
They're common questions, but they're awkwardly imprecise.
What does it mean to be "good" with Linux?
After all, Linux is a big topic.
Technically, it's a kernel.
But in common vernacular, it's also an operating system, a collection of commands, a community, and more.

There are different kinds of familiarity when it comes to Linux.
You might be comfortable using a Linux desktop, but not familiar with terminal commands.
You might know several commands, but only to do a few simple tasks.
Or you might know how to administer a server, but not where to find simple desktop functions.
Regardless of your speciality, they're all useful.