The ``First Industrial Era'' was born out of World War I. Large numbers of men needed to cooperate both inside the army and in business in order to win the war. Thus business was structured very similar to the army and continues to be structured that way to this day. Other innovations included factories, limited liability, trade unions and newspapers. People were easily replaced until the trade unions forced changes in working conditions.
(WW1 story) 
The ``Second Industrial Era'' introduced the ideas of a publicly traded corporation, commercial banks, professional women, and business schools. People expected to be hired, trained, and employed for a lifetime and then retire.
The ``Third Industrial Era'' is today. You personally are your own corporation. You will end up switching jobs every 18 months. Your ``resume'' will be the sum total of your interaction on the web.