An input parameter that lets you parameterize Terraform configurations. Declared with variable {} and assigned via a .tfvars file, environment variables (TF_VAR_), -var flags, or interactively.
In Terraform Associate there are three types: Input variables (input parameters), Local values (reusable expressions), and Output values (exported values). Question: how do you avoid hardcoding a VM size in multiple places? Input variable + local.
Terraform Variable is a concept that can show up on the exam. Check the full guide to see it in context.