Segments allow you to group together customers that have things in common. For example, you might want to create a segment of customers that all purchased from a certain category or that purchased at least 30 days ago.
Segments are dynamic.
This means that if the criteria defined by the segment is removed from the customer, the segment will automatically update and the customer will be removed. And if a customer acquires the criteria defined by a segment, they will automatically get added to the segment.
How long does it take for segments to update?
Segments tend to update immediately. However, segments which rely on more complex criteria have been known to take a little time to reflect any updates.
Learn more about how you can segment your customers here.