Explanation
This is where the Terraform local backend stores its state, by default, unless you specify a different file name or location in your configuration. The local backend is the simplest backend type that stores the state file on your local disk.

Speculative Plans: Terraform Cloud's speculative plan feature runs automatically when changes are detected in a linked VCS repository, enabling users to review potential infrastructure changes without committing them.
Automatic Integration: This feature automates the planning process by triggering when changes are committed, aiding teams in previewing infrastructure changes seamlessly.
For further understanding, see the Terraform Cloud VCS Integration documentation.

Explanation
You can install third party plugins using terraform init, as long as you specify the plugin directory in your configuration or as a command-line argument. You can also use the terraform providers mirror command to create a local mirror of providers from any source.

The terraform fmt command is used to rewrite Terraform configuration files to a canonical format and style. This command applies a subset of the Terraform language style conventions, along with other minor adjustments for readability. Running this command on your configuration files before committing them to source control can help ensure consistency of style between different Terraform codebases, and can also make diffs easier to read. You can also use the -check and -diff options to check if the files are formatted and display the formatting changes respectively2. Running the terraform fmt command during the code linting phase of your CI/CD process can help automate this process and enforce the formatting standards for your team. Reference = [Command: fmt]2

Explanation
The public Terraform Module Registry is free to use, as it is a public service that hosts thousands of self-contained packages called modules that are used to provision infrastructure. You can browse, use, and publish modules to the registry without any cost.