> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sendify.dingstore.cn/llms.txt
> Use this file to discover all available pages before exploring further.

# Dynamic segments

> Build dynamic recipient groups from contact rules

## What is a segment?

A segment is a dynamic recipient group built by filtering contacts with one or more rules. For example, you could create a segment for customers with a March birthday.

![Configure segment rules](https://mintcdn.com/sendify-3a1f7fa4/IaJHUY9fCSXuo_lG/segment-rules.png?fit=max\&auto=format\&n=IaJHUY9fCSXuo_lG\&q=85\&s=61f1a6ac4f37945a8ac7f6cf9ed524ae)

## Automatic updates

Enable **Automatically update data** to add matching contacts to the segment each day at midnight.

## Use segments in a campaign

Select one or more segments when creating a campaign. Contacts that belong to multiple selected segments are counted only once.

![Select segments in a campaign](https://mintcdn.com/sendify-3a1f7fa4/IaJHUY9fCSXuo_lG/select-segments.png?fit=max\&auto=format\&n=IaJHUY9fCSXuo_lG\&q=85\&s=36326c9811e0894962dd5e1afbce5740)

## Segments vs. tags

| | Tags | Segments |
| - | - | - |
| Membership | Applied manually | Matched automatically by rules |
| Updates | Maintained manually | Can update automatically |
| Best for | Stable attributes or ad hoc groups | Dynamic groups based on attributes or behavior |


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