Queuing theory originated in 1908 when a Danish scientist named Agner Krarup Erlang went to work for the Copenhagen Telephone Company and set about trying to determine how many telephone trunks, or lines, were needed to serve callers.
Since then, retail stores, banks, call centers, emergency rooms, manufacturing plants, computer networks and all variety of queuing environments have used Erlang’s formulas or related models to figure out how to manage their lines.
from the Wall Street Journal
There once was a studious Dane
who thought of mankind as a lane.
His theory looked fine
for standing in line;
in practice tis always a pain.