This is what determines how Terraform creates, updates, or deletes resources, as it is responsible for understanding API interactions with some service and exposing resources and data sources based on that API.

State locking prevents other users from modifying the state file while a Terraform operation is in progress. This prevents conflicts and data loss1.

Explanation
This is a secure way to inject sensitive variables into your Terraform run, as they will not be stored in any file or source code repository. You can also use environment variables or variable files with encryption to pass sensitive variables to Terraform.

Explanation
The module source path that does not specify a remote module is source = "module/consul". This specifies a local module, which is a module that is stored in a subdirectory of the current working directory. The other options are all examples of remote modules, which are modules that are stored outside of the current working directory and can be accessed by various protocols, such as Git, HTTP, or the Terraform Registry. Remote modules are useful for sharing and reusing code across different configurations and environments. References = [Module Sources], [Local Paths], [Terraform Registry], [Generic Git Repository],
[GitHub]

You need to write Terraform configuration files for the existing infrastructure that you want to import into Terraform, otherwise Terraform will not know how to manage it. The configuration files should match the type and name of the resources that you want to import.