Environtment Variables	- the environment is an area that the shell builds every time its starts a session. 
                          Environment variables are those that define system properties and allow programs
                          to function correctly. They are available to any child process of the shell. 
                          EX: SHELL = /bin/bash (name of shell we are using)
                              HOME  = /u/eu/dl/kellarso (your home directory) 


Local Variables		- variables that are only present in the current instance or session of the shell. 
                          These can be set at the command prompt and are not accessable to child processes. 
                          EX: NAME="Kellyn", variable named NAME has value of NAME
                              unset NAME, delete variable
                              readonly NAME, make variable read only so that it cannot be deleted or set to
                                             a different value
                              echo $NAME, the $ symbol is needed in order to expand variable to its value