Explanation
Terraform stores the workspace states in a directory called terraform.tfstate.d. This directory should be treated similarly to default workspace state file terraform.tfstate main.tf provider.tf terraform.tfstate.d DEV terraform.tfstate # DEV workspace state file PROD terraform.tfstate # PROD workspace state file terraform.tfvars # Default workspace state file variables.tf

Explanation
Use of remote backends and especially the availability of Terraform Cloud, there are now a variety of backends that will encrypt state at rest and will not store the state in cleartext on machines running. Reference:
https://www.terraform.io/docs/extend/best-practices/sensitive-state.html

https://www.terraform.io/docs/commands/environment-variables.html

Explanation
The Terraform language will automatically convert number and bool values to string values when needed, and vice-versa as long as the string contains a valid representation of a number or boolean value.
Example
* true converts to "true", and vice-versa
* false converts to "false", and vice-versa
* 15 converts to "15", and vice-versa
Where possible, Terraform automatically converts values from one type to another in order to produce the expected type. If this isn't possible, Terraform will produce a type mismatch error and you must update the configuration with a more suitable expression.
https://www.terraform.io/docs/configuration/expressions.html#type-conversion