Essentially, the Linux shell interprets commands so the kernel can understand and use them. Without the shell, not only would commands not work, but applications wouldn't work.

Most Linux distributions default to the Bash shell, which stands for Bourne Again Shell. Why "Bourne"? Because Bourne shell was the first shell, and Bash is an improvement on that. With Bash, you can write bash scripts that can do just about anything. However, Bash has been around for a very long time, and it really hasn't changed much.

The good news is that there are alternatives, and one of those alternatives adds features that Bash has neglected. That shell is called Fish (Friendly Interactive SHell). The big difference between Bash and Fish is that Bash feels like it works for you, and Fish feels like it works with you.

When you run a command in Bash, you type it, hit Enter, and wait to see if it worked. Bash doesn't help you; it just accepts the command and attempts to run it. That's it.

Fish behaves a bit differently. When you start to type a command in Fish, it will offer suggestions (based on your history). When you see a suggestion that works for you, hit the right-pointing arrow key to accept a suggestion. For example, you might type ssh, and Fish will then present a suggestion like ssh 192.168.1.26. Hit the arrow key and then hit Enter.

You might also notice that Fish uses colors. For example, if you type an invalid command, Fish will color it red. If you alter an invalid command to make it valid, it turns blue.