The interface command focuses your configuration on the interface specified
Use the ip command to give the interface a address and a subnet designation
The description command is optional but is very effective in keeping track of what is where
Notice the prompt changes when in interface configuration mode from
R1 (config)# to R1 (config-if)#
The no shutdown command activates the interface
Notice I can move from one interface to the next without backing out with an exit command
The copy running-config startup-config command saves your configuration