## TL;DR

Terraform state (`terraform.tfstate`) is a JSON file mapping real-world resources to Terraform configuration. It is the source of truth for Terraform's understanding of infrastructure. Remote state (S3 + DynamoDB locking) is essential for team collaboration.

## Core Explanation

State locking: DynamoDB prevents concurrent modifications. `terraform import` adds existing resources to state without recreating them. `terraform state mv` moves resources between states. `terraform state rm` removes from state without destroying. State drift detection: `terraform refresh` updates state to match reality. Never edit state manually — use Terraform commands.

## Further Reading

- [Terraform State Documentation](https://developer.hashicorp.com/terraform/language/state)