Since the extinction of dinosaurs several millions of years ago, for human beings, the twentieth has been the century during which there have been a lot of changes, more than in the past. Most of these changes are great, others not so much, and not all of them are good for human beings and the environment. In my opinion, the great change that we should remember about the twentieth century, is the advent of the television, firstly, because individuals since receive directly at their own home images and sounds coming from all around the world. Second, because is a great source of information, and finally, because it's for most persons a leisure source.
Since TV has arrived in homes, people are able to receive videos, images, music, comments, coming from everywhere in the world and this without moving from their sofa. Compared with inventions of past centuries, I find it great. For example, if you lived in the fifteenth century, and someone would have told you that in future it should have been possible to watch though a mirror and see images coming directly from the other world's hemisphere (thanks Copernicus!) you would have certainly thought him crazy.
A great amount of information we receive today in Europe comes from TV. Although, information is transmitted through radio and internet as well, TV remains nowadays the means through which people is much better informed, because by it they have access to images, speeches and video, 24 hours a day. Furthermore, television, for those that have one, is a source of leisure. They stay the evening watching movies, or entertaining programs. For them should be odd to imagine a life without TV.
The great change concerning the last century, I think it is the television because it permits to have access a great amount of...