A generation is a group of people separated by an age of about 25 years although this number is not set. It is generally the average time period that occurs between when a person is born and when reproduction occurs. A generation has the added meaning of drawing differences between the earlier and current generation. In the 1960s the term the generation gap emerged to describe the different in thinking, values, and expectations between the generation then becoming adults and their parents. In the Bible a generation is 40 years.