6.1. Backends: Where State Lives
💡 First Principle: A backend answers one question — "where is the state file, and who can reach it?" — and that single choice determines whether Terraform is a solo tool (local file) or a team tool (shared remote state with locking).
Why care: The local-versus-remote distinction underlies team collaboration, state security, and locking. The exam expects you to know the default, what the backend block does, and why teams move to remote state.
The mental model: A backend is the filing cabinet for state. A local backend is a drawer in your own desk — fine alone, useless to the team. A remote backend is a shared, lockable cabinet everyone draws from, so the team works off one truth.
⚠️ Common Misconception: "You must configure a backend to use Terraform." You don't — without configuration Terraform uses the local backend automatically, writing terraform.tfstate to the working directory. Backends become necessary for collaboration, not for basic operation.
