The industrial revolution is called this because western cultures went through a transformation from being mostly agrarian to being manufacture-based. So, the invention of the steam engine, harnessing of electricity, and development of assembly-line factories had a major impact on how people supported themselves. People moved from the rural areas to the cities to find better paying work in factories. Cities grew large, some people at the top grew very rich, and there was a big jump in social problems caused by the sudden increase in population in the cities.
