# Module

> A reusable, parameterizable collection of infrastructure resources defined in OpenTofu/Terraform.

A *module* is a reusable, parameterizable unit of infrastructure code written in [Hashicorp Configuration Language (HCL)](https://developer.hashicorp.com/terraform/language/syntax/configuration). It encapsulates a set of related infrastructure resources (e.g., a Kubernetes deployment, an AWS VPC) that can be configured and deployed together.

Modules accept *inputs* (also called variables) that control their behavior, and produce *outputs* that can be passed to other modules. This design enables infrastructure patterns to be shared and reused across environments.

In the Panfactum stack, modules are broadly categorized as:

- **Root modules**: Deployed directly via Terragrunt
- **Submodules**: Called as child modules within other modules

And by authorship:

- **Panfactum modules**: Provided by the Panfactum project
- **First-party modules**: Written by your organization
- **Third-party modules**: Sourced from external providers