## Declaring a Local Value

                                                                           A set of related local values can be declared together in a single `locals` block:

                                                                           ```terraform
                                                                           locals { service_name = "forum"
                                                                           owner        = "Community Team"
                                                                           }

The expressions in local values are not limited to literal constants; they can also reference other values in the module in order to transform or combine them, including variables, resource attributes, or other local values:

```terraform
locals
{
  # Ids for multiple sets of EC2 instances, merged together
  instance_ids = concat (aws_instance.blue.*.id, aws_instance.green.*.id)
  }

  locals {
  # Common tags to be assigned to all resources
  common_tags = {
  Service = local.service_name
  Owner   = local.owner
  }
  }