Terraform also automatically loads a number of variable definitions files if they are present:
Files named exactly terraform.tfvars or terraform.tfvars.json.
Any files with names ending in .auto.tfvars or .auto.tfvars.json.
https://www.terraform.io/docs/configuration/variables.html
https://www.terraform.io/docs/configuration/variables.html#variable-definitions-tfvars-files

Explanation
Indent two spaces for each nesting level.
When multiple arguments with single-line values appear on consecutive lines at the same nesting level, align their equals signs.
Reference: https://www.terraform.io/docs/language/syntax/style.html

Reference: https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-types.html

Explanation
If you need to migrate to another backend, such as Terraform Cloud, so you can continue managing it. By migrating your Terraform state, you can hand off infrastructure without de-provisioning anything.
https://www.terraform.io/docs/cloud/migrate/index.html

Explanation
Outputs can be marked as containing sensitive material by setting the sensitive attribute to true, like this:
output "sensitive" {
sensitive = true
value = VALUE
}
When outputs are displayed on-screen following a terraform apply or terraform refresh, sensitive outputs are redacted, with <sensitive> displayed in place of their value.
Limitations of Sensitive Outputs
The values of sensitive outputs are still stored in the Terraform state, and available using the terraform output command, so cannot be relied on as a sole means of protecting values.
Sensitivity is not tracked internally, so if the output is interpolated in another module into a resource, the value will be displayed.