When you use a remote backend that needs authentication, HashiCorp recommends that you:

Terraform variable names are not saved in the state file, only their values are. The state file only stores the attributes of the resources and data sources that are managed by Terraform, not the variables that are used to configure them.

It lets you version, reuse, and share infrastructure configuration as code files, which can be stored in a source control system and integrated with your CI/CD pipeline.
It reduces risk of operator error by automating repetitive tasks and ensuring consistency across environments. IaC does not necessarily provision resources at a lower cost, secure your credentials, or prevent manual modifications to your resources - these depend on other factors such as your cloud provider, your security practices, and your access policies.

You can develop a custom provider to manage its resources using Terraform, as Terraform is an extensible tool that allows you to write your own plugins in Go language. You can also publish your custom provider to the Terraform Registry or use it privately.

The correct way to reference an attribute from the vsphere_datacenter data source for use with the datacenter_id argument within the vsphere_folder resource in the following configuration is data.vsphere_datacenter.dc.id. This follows the syntax for accessing data source attributes, which is data.TYPE.NAME.ATTRIBUTE. In this case, the data source type is vsphere_datacenter, the data source name is dc, and the attribute we want to access is id. The other options are incorrect because they either use the wrong syntax, the wrong punctuation, or the wrong case. Reference = [Data Source:
vsphere_datacenter], [Data Source: vsphere_folder], [Expressions: Data Source Reference]