Also consider reading bootstrap/README.md.
This document’s purpose is to explain how to bootstrap Terraform for a new organization, or a new AWS account. Because our goal is to explicitly manage everything in Terraform, we somehow need to create the S3 bucket that is used for storing the state files of all of our other projects.
The bootstrap project is a simple Terraform project that uses the local backend with a state file that is commited to Git. That is the sole purpose of this Terraform project, and everything else should therefore use the remote S3 backend using this bucket as the state file bucket.