AWS CloudFormation is a the Infrastructure as Code offering of Aws. It's categorized as orchestration tool.
You declare resources in CloudFormation Templates and AWS CloudFormation takes care of provisioning and configuring those resources for you.
CloudFormation is a Amazon technology for defining a cloud stack as a JSON document.
When you use AWS CloudFormation, you work with:
An AWS CloudFormation template is a JSON or YAML formatted text file that declares Aws resources (VM, network, …)
A stack is a collection of AWS resources that you can manage as a single unit.