This is Part-04 of Developer's Guide to Terraform in this section we are going to discuss about the Terraform Plan Command.
The terraform plan command creates an execution plan, which lets you preview the changes that Terraform plans to make to your infrastructure. By default, when Terraform creates a plan it:
Reads the current state of any already-existing remote objects to make sure that the Terraform state is up-to-date.
Compares the current configuration to the prior state and noting any differences.
Proposes a set of change actions that should, if applied, make the remote objects match the configuration.