A platform team deploys the same set of components, network, cluster and service, together in many environments and regions. They want to define the components once, deploy them as a unit in HCP Terraform with each environment customized by inputs, and roll a change out environment by environment. Which feature fits?

Terraform Stacks are a configuration layer in HCP Terraform designed for repeatedly deploying the same infrastructure. A Stack splits configuration into components, defined with component blocks in a component configuration file, each sourcing a Terraform module and configured through inputs; all components in a Stack share a lifecycle. A separate deployment configuration file defines deployment blocks, one per environment, account or region, each customized with input values. HCP Terraform then manages the Stack as a unit, rolls configuration changes out to each deployment, tracks changes across environments, and can use orchestration rules to auto-approve deployment runs that meet conditions. CLI workspaces repeat state for one directory but share one backend and offer no orchestration across environments. A single workspace with for_each over every environment and region puts everything in one state, so every change plans against all environments at once and one error can affect them all. Run triggers sequence separate workspaces after successful applies, but each workspace remains independent, so there is no single unit or per-deployment rollout. Exam caveat: Stacks and workspaces can coexist in the same project, and Stacks are an alternative to workspaces rather than a feature added to them. Operational check: write the component and deployment files, create the Stack in HCP Terraform, and confirm a change is planned separately for each deployment.