How do dynamic segments differ from static ones?

Dynamic segments recalculate membership continuously based on defined criteria. When a subscriber's behavior or attributes change, they automatically enter or exit the segment. This ensures the audience always reflects current reality without manual intervention.

Static segments are fixed lists created at a specific point in time. The membership remains unchanged unless someone manually adds or removes contacts. They capture a snapshot rather than a living definition.

Use dynamic segments for ongoing campaigns where relevance depends on current status, such as active customers, recent browsers, or subscribers approaching a milestone. Use static segments for one time campaigns or tests where you need consistent membership throughout the analysis period.

Static segments are also useful for holdout groups. Once you define a control group, you don't want members drifting in and out based on behavioral changes. The fixed membership preserves test integrity.

Most ESPs support both types. Dynamic segments are the flowing tide that reshapes the coastline daily. Static segments are the marked charts that record where the shore stood on a specific day.