## External Data Segments
An external data segment (also known as a data pixel) is the output of a pixel mapping process that results in the creation of a single, permissioned audience segment. In contrast to a permissioned taxonomy, which can be managed via API and contain N segments, an external data segment represents one audience segment and is defined within the Onboard section of the Audiences module in MediaMath Platform.
External data segments are permissioned to specific agencies (MediaMath entity structure): organization > agency > advertiser) so all advertisers within the agency will have access to the external data segment. Prior to getting started, the data provider needs to be added to the agency in MediaMath Platform. To have a data provider added, contact your MediaMath representative.
If the data provider already has the appropriate access, follow these steps to get your external data segments created:
1. Define an audience segment by creating an External Data Segment in the Onboard tab within the MediaMath Platform Audience module.

![MediaMath Platform Data Pixel](https://mediamath.github.io/api-docs/images/t1_data_pixel_form.png)
1. Provide the pixel IDs created in step 1 to your data provider.
2. Data provider will then submit a ticket directly to `pixelmapping@mediamath.com`, including the following. Include each external data segment mapping in the body of the email (or Support ticket) in the line-separated format below.

**Note:** Requests to `pixelmapping@mediamath.com` are handled via an automated process, as long as the formatting below is followed in the subject and body of your email. If the format does not conform, requests will be handled within 1 business day.
External Data Segment Example Request
> Subject Line: Data Provider Pixel Mapping Request
Description:
Please map the following
ns:8473,mm:679001
ns:8474,mm:679002
ns:8675,mm:679003

ns = the name space of the first pixel being mapped, refer below or reach out to MediaMath support if the namespace is unknown.
mm = MediaMath Namespace. This will always be "mm" in the mapping request.
XXXXXX = the partner's segment code sent to MediaMath via S2S.
YYYYYY = the MathTag ID ("MT_ID") associated with the MediaMath external data segment pixel created in step one.