What are variables used for in Terraform?

Variables in Terraform serve the essential purpose of providing dynamic values and configurations that can be reused and parameterized within your infrastructure code. This allows for more modular and flexible configurations, enabling users to define certain values once and then reference those variables throughout their Terraform configuration files.

By using variables, you can make your Terraform scripts adaptable to different environments and scenarios without hardcoding specific values in the configuration files. For instance, variables can specify the instance type for an AWS EC2 instance or the region where resources will be deployed. This approach also enhances collaboration and ease of management, as different users or environments can supply different values for these variables depending on their specific requirements.

The other options do not represent the primary function of variables in Terraform. Storing state files pertains to tracking and managing the current state of your infrastructure. Managing user permissions involves configuring access controls, which is separate from variable management. Authenticating API requests is a function that typically involves different mechanisms such as access tokens or keys, rather than being handled through variables.