When you are working in a shell you certainly don't want to waste your time using arrow keys or home/end keys to navigate around the command line. One of the most popular shells, bash - Bourne Again SHell, uses GNU's Readline library for reading the command line. The GNU Readline library provides a set of functions for use by applications that allow users to edit command lines as they are typed in
![Bash Emacs Editing Mode Cheat Sheet](https://cdn-ak-scissors.b.st-hatena.com/image/square/deedb67dac356f5b6b3e505320e371d9688b51b1/height=288;version=1;width=512/https%3A%2F%2Fcatonmat.net%2Fimages%2Fcatonmat-preview-image.png)