LANs simply link computers in order to share resources within a closed environment. The first software programs that ran on a LAN were not capable of being used by more than one user at a time. Wide area networks $($WANs$)$ first implemented with $\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$ at massive government expense, started attracting PC users as networks went to this new level.