During How to Make (almost) Anything, you may find yourself typing a bunch of commands in the terminal. This tutorial provides some snippits of explainations from other sites with links for those who'd like to find out more. There's a good set of beginner tutorials here.

The following is from this website - The UNIX shell program interprets user commands, which are either directly entered by the user, or which can be read from a file called the shell script or shell program. Shell scripts are interpreted, not compiled. The shell reads commands from the script line per line and searches for those commands on the system, while a compiler converts a program into machine readable form, an executable file - which may then be used in a shell script.

Apart from passing commands to the kernel, the main task of a shell is providing a user environment, which can be configured individually using shell resource configuration files.

bash = Bourne Again shell. Bash is the GNU shell. The GNU project (GNU's Not UNIX) provides tools for UNIX-like system administration which are free software and comply to UNIX standards.

bash commands

CommandWhat it does
chmodChange access permissions
bgSend to background
cpCopy files to another location
duEstimate file space usage
echoDisplay message on screen
jobsList of current jobs
makeRecompile a group of processes
sudoExecute a command as another user
touchChange file timestamps, also use to create empty files
wgetRetrieve web pages

Full set of commands here.