A developer will author an AWS CloudFormation template locally and then deploy the CloudFormation stack to AWS. What is required on the developer’s machine to perform these tasks?

To deploy a CloudFormation stack from a local machine, the developer needs a way to interact with AWS services. The AWS CLI (Command Line Interface) is the standard tool for this. Once installed, the CLI requires authentication to authorize actions. This is typically done by configuring it with an IAM user's access key ID and secret access key. These credentials allow the CLI to make API calls on behalf of the user. Using an IAM user name and password is for logging into the AWS Management Console, not for programmatic access via the CLI. An SSH key is used for secure shell access to EC2 instances, not for authenticating the AWS CLI. While an AWS SDK could be used programmatically, the question specifically asks about authoring a template and deploying a stack, which is a common use case for the AWS CLI. X.509 certificates are generally used for client-side authentication in specific scenarios, not for general AWS CLI configuration.