Linux System Introduction
If you've primarily used computers through a graphical interface, Linux may initially feel very "command-line." This material helps you build a big-picture understanding first: what Linux is, what components make up the system, and which concepts will come up again and again in daily use.
There's no rush to memorize commands here -- it's better used to establish a background framework. When you later look at paths, permissions, environment variables, and Shell, each page won't feel like an isolated piece of knowledge.