The generation gap is a popular term used to describe differences between people of a younger generation and their elders, especially between a child and his or her parent's generation. The term first became popularized in Western countries during the 1960s and described the cultural differences between the young and their parents.
Although some generational differences have existed throughout history, because of more rapid cultural change during the modern era differences between the two generations increased in comparison to previous times, particularly with respect to such matters as musical tastes, fashion, culture and politics. This may have been magnified by the unprecedented size of the young generation during the 1960s, which gave it unprecedented power, and willingness to rebel against societal norms.
This can be seen in songs such as the 1965 hit "My Generation" by The Who.