Segmentation works when the groups behave differently, not just look different

Splitting an audience by age or country feels tidy and organised, but often it changes nothing about the message you actually send them.

Segment instead by behaviour that predicts action:
• the specific job the customer is hiring the product to do
• how urgently they feel the underlying problem in daily life
• what clumsy workaround they currently rely on
• what would make them switch away from that workaround

A good segment is a group that responds to the same message for the same reason, not one that shares a birthday.

A simple example: two buyers of the exact same age may want opposite things, so age alone is a weak and misleading line to draw between them. Behaviour tells the truer story.