AWS Free Usage Tier (Global-DataTransfer-Regional-Bytes)

As a new AWS user, it's important to understand that stopping an EC2 instance doesn't necessarily stop all associated costs. Even when an instance is stopped, certain resources may continue to accrue charges or count towards your free tier usage limits.

In your case, the "Global-DataTransfer-Regional-Bytes" usage likely refers to data transfer between AWS services within the same region. This can occur even when your EC2 instance is stopped, as other associated resources might still be active.

To address this issue and prevent further consumption:

1. Make sure you've properly terminated (not just stopped) your EC2 instance if you're no longer using it.

2. Check for any associated resources that might still be active, such as Elastic IP addresses, EBS volumes, or load balancers. These can continue to generate data transfer even when your instance is stopped.

3. Review your EC2 dashboard to ensure you don't have any running instances in other regions.

4. Check your VPC settings and see if there are any NAT gateways or other networking components that might be generating traffic.

5. Set up AWS Budgets or Free Tier usage alerts to notify you when you're approaching your limits.

6. Regularly monitor your usage through the AWS Billing Dashboard to track your consumption and stay within the Free Tier limits.

Remember, while AWS offers a generous free tier, it's crucial to understand which actions might lead to billable services or count towards your usage limits. If you're unsure about any resources or charges, it's best to terminate or delete them if you're not actively using them for your learning purposes.
Sources
Billing misunderstand | AWS re:Post
Free tier Ec2, how to avoid overages | AWS re:Post