When the state file is locked, operations that modify or depend on the state (like terraform apply, terraform destroy, and terraform state list) are blocked. terraform fmt only formats the configuration files and does not interact with the state, so it is allowed.
References:
Terraform State Locking

Explanation
This is how you specify a module's version when publishing it to the public Terraform Module Registry, as it uses the tags from your version control system (such as GitHub or GitLab) to identify module versions. You need to use semantic versioning for your tags, such as v1.0.0.

Terraform Cloud provides features like remote state storage and a web-based user interface for managing your Terraform runs. While it offers robust infrastructure as code capabilities, automatic backups of configuration and state are not directly provided by Terraform Cloud; instead, the state is stored remotely and secured.
Reference:
Terraform Cloud Features

When declaring a Terraform output, thevalueargument is required. Outputs are a way to extract information from Terraform-managed infrastructure, and thevalueargument specifies what data will be outputted. While other arguments likedescriptionandsensitivecan provide additional context or security around the output, valueis the only mandatory argument needed to define an output.References= The requirement of thevalue argument for outputs is specified in Terraform's official documentation, which provides guidelines on defining and using outputs in Terraform configurations.