Linux is a powerful operating system. It can be an incredible time sink for those less experienced or looking for copy/paste commands. Hours to accomplish simple tasks. Usually, a better understanding helps get everything done, but a lot of the time, a quick fix or command reference is good enough.
Ubuntu is probably the most popular Linux distribution, so this section will mainly focus on it. Most, if not all, of the tips, tricks, and program guides will happily work on other Debian-based distributions and possibly more than just Debian-based distros.
Always learn more, especially in a production environment. This is just for reference.