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

# Data masking

> Data masking protects sensitive columns by controlling how each one can be viewed, used in audiences, and synced. Hightouch flags likely personally identifiable information (PII) for review, and you assign a privacy level that governs the column everywhere it's used.

## Before you begin

* [Set up for platform admins and data teams](https://docs.hightouch.com/customer-studio/overview.md#for-data-teams-and-platform-admins)

## Overview

Data masking lets you classify sensitive columns and control how each one can be used across Hightouch. You assign every column a privacy level, and that level applies wherever the column appears: profiles, filter suggestions, analytics, agent responses, and syncs.

You manage privacy levels on the **Data masking** page, under **Customer Studio > Governance**. You can set the same level per column [as you build your schema](https://docs.hightouch.com/customer-studio/schema.md#set-privacy-levels-for-columns).

Data masking controls **columns and values**. To restrict which **rows** a user can access instead, use [subsets](https://docs.hightouch.com/customer-studio/subsets.md).

## Privacy levels

Every column has a privacy level. Assign one based on how sensitive the data is and where it's allowed to be used.

| Privacy level | What it does | Use for |
| - | - | - |
| **Unreviewed** | Behaves normally until you classify it. This is the default. | Columns you haven't reviewed yet. |
| **Approved** | No restrictions. Cleared through your review process. | Non-sensitive data. |
| **Redacted** | Values are hidden from users in the app, but the column can still be used in syncs and audience logic. | Data you can sync but shouldn't show users, such as email addresses. |
| **Sync-only** | Syncs to destinations, but isn't visible or usable in the app. | Values needed downstream but never in Hightouch. |
| **Sync-blocked** | Usable inside Hightouch, but never synced to any destination. | Internal attributes that must not leave the warehouse. |
| **Blocked** | Never synced, displayed, or used downstream. | Highly sensitive data that must stay fully restricted. |

![Privacy levels](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/data-masking/privacy-level-list.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=9dfa780df7e70b1e7af383daf1d479d3)

## Review flagged columns

Hightouch automatically flags columns that look like PII and marks them with a warning icon for review. Flagging only applies to unreviewed columns, so it never overrides a level you've already set.

Filter by **PII review** for the columns that need review, check each one, and assign the correct privacy level.

![PII flagged column](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/data-masking/pii-flag.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=956bb733030402df1bb1f85b76b58aeb)

## Set a privacy level

Go to **Customer Studio > Governance > Data masking**. The table lists every column, sorted by most recently updated. Search or filter by model, source, PII category, privacy level, or PII review status to find the columns you want.

![Data masking table listing columns with their model, source, PII category, and privacy level, with the filter rail open](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/data-masking/privacy-page.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=223ccfa31b5dd5db115008caa90d8022)

Find the column you want to classify, then set its level from the **Privacy level** dropdown on that row. The change takes effect as soon as you select a level, and clears any PII flag on the column.

To keep an audit record or review classifications outside Hightouch, select **Export CSV**. The download lists each column with its model, source, PII category, and privacy level, and respects the filters you've applied.

## Categorize columns

Assign a category to group and filter related columns, such as `Email`, `Name`, `Birthdate`, `Address`, `Phone`, or `IP address`. Categories make it easier to review and manage PII across a large schema.

![PII categories](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/data-masking/pii-category.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=f634d118f6a6706eb17cecdb4f2540d4)

## Permissions

Data masking is controlled by schema permissions. To edit privacy levels and categories, a user must have `Configure schema` access on the source.

![Data masking configure schema permissions](https://mintcdn.com/hightouch-3c037897/L_vQfA0JQEpeGUUo/images/hightouch-audiences/data-masking/data-masking-configure-schema-permissions.png?fit=max\&auto=format\&n=L_vQfA0JQEpeGUUo\&q=85\&s=1966c59493b363ffcc91eb6cfaeaa7af)

See [source-level permissions](https://docs.hightouch.com/workspace-management/roles.md#sources) for details.

## Next steps

* [Usage](https://docs.hightouch.com/workspace-management/lineage.md) to see which audiences, syncs, and journeys depend on a column before you change its privacy level.
* [Subsets](https://docs.hightouch.com/customer-studio/subsets.md) to restrict which rows of data each user can access.
* [Define your schema](https://docs.hightouch.com/customer-studio/schema.md#set-privacy-levels-for-columns) to set privacy levels as you build the schema.
* [Destination rules](https://docs.hightouch.com/customer-studio/destination-rules.md) to control which records can reach a given destination.