Segments

A segment is a saved filter over your contacts' attributes and tags — a living audience that recomputes as contacts change, not a static list. "Pro users in the EU", "trialists who never activated", "customers who bought twice".

How membership works

A segment is defined by the same filter grammar automations use: conditions over contact.attributes.* and contact.tags, combined with and / or groups. A contact is a member whenever their current attributes satisfy the filter — there is no manual add/remove.

Segment-entry triggers

When a contact's attributes change so they newly match a segment (a false→true edge), the platform emits a synthetic $segment_entered event. An automation triggered on $segment_entered, filtered to a specific segmentId, enrolls the contact the moment they qualify — still throttled and suppression- checked, never a blast.

trigger:  $segment_entered
filter:   event.properties.segmentId = "<segmentId>"

This is how "when someone becomes a power user, start the advocacy sequence" works without your app emitting a custom event.

Where segments show up

• The dashboard's Segments page, to define and inspect audiences.
• Over MCP, as filter targets and $segment_entered automation triggers.

See Automations for how triggers and filters fit together.