A segment is a group of people. You can segment participants based on various factors - interest, location, demographics, etc. and quickly access all participants in that area to re-engage them through email outreach.
Below are the selection criteria that you can use to create different segments.
Another way segments are useful for data analysis is that it enables you to group people in order to filter a dynamic report.
The use of segments for data analysis has unlimited potential for actionable insights into the participants in your surveys.