As we will see later the Internet relies on packets to transfer data.
The origin is military : for utmost security in transferring information of networks (no single outage point).
Data is split into tiny packets that may take different routes to a destination.
Hard to eavesdrop on messages.
More than one route available -- if one route goes down another may be followed.
Networks can withstand large scale destruction (Nuclear attack - This was the time of the Cold War).