# Creating Dynamic Segments
## Description

Segmentation involves grouping your recipients according to their needs and responses to a particular marketing effort. Businesses use market segmentation to target different categories of consumers who perceive specific products and services in different ways according to their preferences and other characteristics that can be detected.

## Why It's Important
You can tailor your lists according to your needs using various segmentation methods such as geographic, demographic, and behavioral segmentation. Discover which campaigns will likely get an excellent response from a target market and the best ways to tag and deliver these emails. As a result, the marketing effort can increase its effectiveness.

## Step-by-Step Process
To create a new segment from a list:

<Stepper>

1. In the left menu, select **Audience**, then **Contacts**

1. Choose your list

1. Select the **Create a segment** option

1. Your segmentation conditions can be defined here. The first thing to do is name your segment

1. You can segment your list based on the conditions you choose:
   - **Contact ID:** The identification number that is automatically assigned to contacts. According to their order of addition, they are numbered starting from 1
   - **Email address:** Your contact's address
   - **Date added:** You can set rules based on the date your contacts were added. For example, before, after, or on a specific date
   - **Email activity:** Your contacts can be sorted by their email activity. For example, when they received emails, which emails they opened, and which recipients clicked on the email
   - **Link activity:** You can sort your contacts based on which email links were clicked
   - **Custom attributes:** You can add attributes based on your segmentation preferences. Here's how to add an attribute to a contact

1. You will see the total number of recipients on the list displayed next to the segment name when you create your segment

1. Once finished, click **Save and exit**

1. After the group has been successfully created, you will see it available under your contact list.
You can also edit the group name and rules and see the number of subscribers by selecting **VIEW ALL SEGMENTS**
</Stepper>

![Segment builder: name your segment, choose a list, then add conditions in the Conditions box (with AND/OR logic via "Or contacts must match this new set of conditions") before saving](/images/audience/creating-dynamic-segments.png)

## Combining Conditions: AND vs OR

How you combine conditions changes the size of your segment:

| | AND | OR |
|---|---|---|
| **Contacts included** | Contacts who match **all** the conditions | Contacts who match **at least one** of the conditions |
| **Effect on the segment** | Smaller (the intersection of the groups) | Larger (the groups added together) |
| **Example** | Tag "VIP" **and** city "Montreal": only VIP contacts who live in Montreal | Tag "VIP" **or** city "Montreal": every VIP contact, plus every contact in Montreal |

- Conditions in the same set are combined with **AND**: contacts must match every condition in the set.
- To add an **OR**, click **+ Or contacts must match this new set of conditions**. Contacts who match either set are included.

If your segment is smaller than you expected, you probably used AND where you meant OR.

## Segments Update Automatically

A segment is not a fixed copy of your contacts. Once you save it, it updates by itself: when a contact starts matching the conditions (for example, a new subscriber picks the interest "Events", or a contact receives a tag), they join the segment. When they stop matching, they leave it. You don't need to rebuild the segment before each campaign.

## Sending a Campaign to Several Segments

A campaign is sent to **one list**. In the campaign's recipient step, you choose the list, then you can narrow it down by selecting one or more segments of that list. This is another reason to keep your contacts in one list with several segments, rather than in several lists. See [Managing contact lists](/en/docs/audience/managing-contact-lists).

## Troubleshooting

**My segment is smaller than expected**

- Check how your conditions are combined. With **AND**, contacts must match every condition. Use **OR** (**+ Or contacts must match this new set of conditions**) to include contacts who match any of them
- Check that the values you filter on are spelled exactly as they are in your list (tag names, attribute values)
- Check which list the segment is built on. A segment only includes contacts from its own list


**Segment shows zero contacts**

- Review your segmentation rules for conflicts
- Check date formats (must be YYYY-MM-DD)
- Make sure conditions aren't too restrictive
- Check that contacts meet all criteria when using "AND" conditions

**Segment doesn't update automatically**

- Allow time for the system to process changes
- Check if contacts were added after segment creation
- Refresh the page or log out and log back in
- Check that email activity data is being tracked correctly

**Unable to create new segments**

- Check your plan limits for segments
- Make sure the segment name is unique within the list
- Check that you have the necessary permissions
- Try creating a simpler segment first to test

**Email activity criteria not working**

- Make sure campaigns have been sent to generate activity data
- Check if tracking pixels are being blocked
- Check the date range for activity criteria
- Wait 24-48 hours for activity data to be fully processed

**Custom attribute filters don't appear**

- Confirm attributes exist for the selected list
- Check that attributes have data to filter on
- Make sure attribute types match filter options
- Try refreshing the segment creation page

**Segment takes too long to process**

- Simplify complex rule combinations
- Break large segments into smaller ones
- Avoid using too many "OR" conditions
- Contact support for segments over 100k contacts

## Related Articles

- [Add attributes to your list](/en/docs/audience/adding-attributes-to-your-list) - Segment by custom fields
- [Create and use tags](/en/docs/audience/using-tags-to-track-engagement) - Alternative segmentation method
- [Tags, interests, or attributes: which one to use](/en/docs/audience/tags-interests-or-attributes) - Choose what to segment on
- [Create and manage a contact list](/en/docs/audience/managing-contact-lists) - List management basics
- [Personalize your campaign with display conditions](/en/docs/personalization/display-conditions) - Use segments for personalization
- [Understand contact status](/en/docs/audience/contact-status) - Segment by engagement