# Data Policies

Data policies determine what users see when they query data in a table they have access to.

## [Overview](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/data-policy-overview)

This guide provides a general overview of data policies and their behavior.

## How-to guides

* [Author a masking data policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/data-policy-tutorial)
* [Author a minimization policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/minimization-tutorial)
* [Author a purpose-based restriction policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/purpose-tutorial)
* [Author a restricted data policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/restricted-data-policies)
* [Author a row-level policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/row-redaction-tutorial)
* [Author a time-based restriction policy](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/time-based-tutorial)
* [Certification, exemptions, and diffs](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/manage-policies-per-data-source): Certify policies, exempt users from policies, and view policy diffs on a data source.
* [External masking interface](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/how-to-guides/external-masking-interface): Set up Immuta to use the encryption or masking algorithm in your external masking service.

## Reference guides

* [All data policy types](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/data-policies): This guide describes all the data policies available in Immuta.
* [Masking policies](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/masking-matrix-functions): This guide describes the types of masking policies available and when to use each.
* [Row-level policies](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/row-redaction-explained): Row-level policies compare data values with user metadata at query-time to determine whether or not the querying user should have access to the individual rows of data.
* [Custom WHERE clause functions](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/custom-where-clause-functions): This guide describes the custom functions you can use to extend the PostgreSQL WHERE syntax.
* [Data policy conflicts and fallback](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/data-policy-conflicts): In some cases, two conflicting global masking policies apply to a single data source. This guide describes how Immuta handles those conflicts.
* [Custom data policy certifications](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/custom-policy-certifications): When building a global data policy, governors can create custom certifications that must be acknowledged by data owners when the policy is applied to data sources.
* [Orchestrated masking policies](https://documentation.immuta.com/2024.3/secure-your-data/authoring-policies-in-secure/data-policies/reference-guides/orchestrated-masking-policies): These policies reduce conflicts between masking policies that apply to a single column, allowing policies to scale more effectively across your organization.