A configuration that defines where Terraform state is stored. Remote backends (S3, Azure Blob Storage, HCP Terraform) enable team collaboration and state locking to avoid conflicts.
In Terraform Associate: without a remote backend, state is local and can't be shared with the team. With an S3 backend, state locking is enabled with use_lockfile = true (Terraform 1.11+; the DynamoDB method is deprecated). Question: how do you prevent two people from applying changes at the same time? State locking with a remote backend.
Terraform Backend is a concept that can show up on the exam. Check the full guide to see it in context.