New terms and their definitions: Course module Android: a mobile operating system based on Linux Application

Groups: A collection of users
GUI: A graphical user interface
Hidden files: A set of files that are not visible either to avoid alteration or simply because you don’t want someone to see them
Hot key: A keyboard shortcut that does a particular task
I/O Streams: An input stream handles data flowing into and out of a program
Parameter: A value that is associated with a command 
Parent directory & child directories: A parent directory is a directory that houses all subsequent child directories
Paths: A main directory that branches off and holds other directories and files
Prompt: A prompt shows you which directory you’re currently in
Regular expression: A pattern matching language that describes words, phrases, or more complicated patterns; regular expressions are used to help you do advanced pattern based selection
Relative path: It is a path from your current directory
Root directory: A parent directory for all other directories in a file system
Shell: A shell is a command line interpreter for Linux
Standard error (stderr): A data stream that redirect the output of error messages in a different output stream. It works both in Linux and Windows
Standard In (stdin): A data stream in which the input that you provide through the keyboard goes to the standard in stream of the process that you're interacting with. It works both in Linux and Windows
Standard out (stdout): A data stream that when a process creates output, it adds data to the standard out stream, which flows out of the process. It works both in Linux and Windows
Stdin, stdout, stderr: Three data streams created when you launch a Linux command
Subdirectories: A directory below or at a deeper level in the directory hierarchy
Tab completion: A way to auto-complete a command or file names and directories