Terraform modules are a collection of .tf files that are used together to deploy a resource. A Terraform configuration contains at least one module (root module). When a root module calls another module, it is often known as a child module. Below is an example of a module.
In this workshop we will use 3 modules (workspace/vpc/db) to build a tf deployment. The module we referenced is open-sourced. They part of a catalog of modules published on AWS Infrastructure and Automation catalog.
A link to the AWS Terraform Modules Catalog is provided in the navigation bar to the left of your screen