PostEaseThe short answer
Audience segmentation is the practice of dividing a broader audience into smaller groups based on shared characteristics (interests, behavior, demographics, or where they are in a buying decision) rather than treating an entire following as one uniform group.
Why a single following usually is not one uniform group
A business account's followers often include existing customers, people who have never bought anything, competitors, and people who follow for reasons unrelated to purchasing. Content and offers built for one segment can land poorly with the others, or go ignored entirely.
How this plays out in practice on social media
Organic social content is broadcast to an entire following, not to a specific segment the way targeted email or ads can be. So segmentation here shows up in content strategy rather than targeting: varying content deliberately to speak to different segments across a broader mix, instead of writing every post for one imagined "average" follower.