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.

Terraform keeps track of the infrastructure state via the state file. When you initially ran terraform plan, Terraform determined that the port should be changed from80 to 443. However, since another team member manually modified the load balancer, Terraform's local state file is now outdated.
* When you run terraform apply, Terraform willcompare the expected state (from the plan) with the actual state (from the provider API).
* Since the port is already set to443, but the local state file still shows80, Terraform willfail with an errordue to the state mismatch.
* To resolve this, you should run terraform refresh or use terraform apply -refresh-only to update the local state before applying changes.
Official Terraform Documentation Reference:
State Management - HashiCorp Documentation
Managing Drift in Terraform

The public Terraform Module Registry is free to use, as it is a public service that hosts thousands of self-contained packages called modules that are used to provision infrastructure. You can browse, use, and publish modules to the registry without any cost.

The command that makes your code more human readable is terraform fmt. This command is used to rewrite Terraform configuration files to a canonical format and style, following the Terraform language style conventions and other minor adjustments for readability. The command is optional, opinionated, and has no customization options, but it is recommended to ensure consistency of style across different Terraform codebases. Consistency can help your team understand the code more quickly and easily, making the use of terraform fmt very important. You can run this command on your configuration files before committing them to source control or as part of your CI/CD pipeline. References = : Command: fmt : Using Terraform fmt Command to Format Your Terraform Code

This is what will happen if you run terraform destroy without any flags, as it will attempt to delete all the resources that are associated with your current working directory or workspace. You can use the -target flag to specify a particular resource that you want to destroy.