Introduction
In order to apply infrastructure changes using Terraform in continuous way, we need to configure some place where current state of your infrastructure will be stored.
Simplest and cheapest way is to use hosted Postgres in PaaS products like Supabase, which will be covered in a guide.
You can also specify a different backend, which might make more sense, when for example, you already use AWS and it's easier for you to manage S3 buckets instead of Supabase.
info
It is not recommended nor safe to delegate this to any no-name tool, which promises to store it for you. This state file might contain sensitive secrets, it is better to self-manage it.