---
schema_version: "1"
id: 0c09d1386580e6456159a16a5f7e939baf1e99acc990d16ed78cdc98fa57a27a
title: Contact Builder Data Sources
collection: admin
version: current
locale: en-us
portal_url: https://docs.salesforce.com/admin/current/en-us/mktg/264-0-0/mc_cab_data_sources.md
canonical_url: https://help.salesforce.com/s/articleView?id=mktg.mc_cab_data_sources.htm&release=264.0.0&type=5
source_site: help.salesforce.com
content_type: documentation
content_hash: adf3fe7eb6fd5a2196b6c8fe49a8d4cfd6e539f5b731e6df386f6543ac3c8675
description: Data sources in Contact Builder indicate where your account stores and locates contact attributes. To determine the origin of the attribute values that you use to filter and segment contacts, use data sources in Marketing Cloud Engagement. When you know the origin, you can use the most recent and effective data to connect your attribute groups for your communication activities. For example, you can tag customer purchasing data as arriving from an outside source. Other users acting on this data can then identify the custom data source and use the most up-to-date data in your activities.
products:
  - Marketing
  - Marketing Cloud Engagement
release: "264"
---
# Contact Builder Data Sources

Data sources in Contact Builder indicate where your account stores and locates contact attributes. To determine the origin of the attribute values that you use to filter and segment contacts, use data sources in Marketing Cloud Engagement. When you know the origin, you can use the most recent and effective data to connect your attribute groups for your communication activities. For example, you can tag customer purchasing data as arriving from an outside source. Other users acting on this data can then identify the custom data source and use the most up-to-date data in your activities.

Data sources includes three types of locations.

- System
- Synchronized
- Custom

## System Data Sources

System data sources represent default data structures created in Marketing Cloud Engagement. Listed data sources vary depending on the functionality in your account, such as Email Studio, mobile applications, and Personalization Builder.

## Synchronized Data Sources

Synchronized data sources use Marketing Cloud Connect to move data from another Salesforce cloud into Engagement. The connector regularly receives updates from the external source to ensure that consistent data is available for use. Use synchronized data sources to include external data in your marketing activities while maintaining a separate database of record elsewhere.

Synchronized data sources require Contact Builder and Marketing Cloud Connect. This functionality also supports standard and custom objects only from within Salesforce.

Synchronized data sources work with field-level encryption to encrypt data. If you encrypt a field within the Salesforce source object, synchronized data sources detects that encryption setting and encrypts the value in Engagement, as well. Contact your account executive to enable field-level encryption.

Accounts that integrate with Google Analytics and Audience Studio also view those audiences on the Data Sources tab. To view and share information about audiences, use the tiles in the External Audiences section.

## Custom Data Sources

Custom data sources collect attributes used with Contact Builder and visually link those attributes to a specific data source. The data source identifies where the attribute values originate.

- **[Synchronized Data Sources in Contact Builder](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_data_integration_for_your_account_with_synchronized_data_sources.htm&release=264.0.0&type=5)**  
    Synchronized Data Sources in Contact Builder bring data from Salesforce into Marketing Cloud Engagement. At defined time intervals, they synchronize data from your Salesforce account, including data schemas and relationships previously established in your Salesforce CRM account.
- **[Create Custom Data Sources in Contact Builder](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_creating_and_interacting_with_custom_data_sources.htm&release=264.0.0&type=5)**  
    Follow these steps to create custom data sources in Contact Builder.
- **[Assign Attributes to a Custom Data Source](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_assign_attributes_to_a_custom_data_source.htm&release=264.0.0&type=5)**  
    Follow these steps to assign an attribute to a custom data source in Contact Builder.
- **[View Attributes Assigned to a Custom Data Source](https://help.salesforce.com/s/articleView?id=mktg.mc_cab_view_attributes_assigned_to_a_custom_data_source.htm&release=264.0.0&type=5)**  
    Follow these steps to view attributes assigned to a custom data source in Contact Builder.