AWS CloudFormation is a service provided by Amazon Web Services (AWS) that allows you to define and provision your AWS infrastructure as code. It enables you to create and manage AWS resources using declarative templates, making it easier to automate and manage your infrastructure deployments.

Here are the key features and concepts related to AWS CloudFormation:

1. Infrastructure as Code (IaC): CloudFormation allows you to define your infrastructure using templates written in JSON or YAML format. These templates are version-controlled, human-readable files that describe the desired state of your AWS resources, including EC2 instances, databases, networking, security groups, and more.

2. Declarative Templates: CloudFormation templates describe the desired end state of your infrastructure rather than specifying the step-by-step procedures for provisioning resources. You define the resources, their properties, and dependencies, and CloudFormation handles the creation, updating, and deletion of resources to ensure the desired state is achieved.

3. Stack: A stack is a CloudFormation resource unit that represents a collection of AWS resources created from a template. You create, update, or delete stacks to manage your infrastructure. Stacks can be created using the AWS Management Console, AWS CLI, or CloudFormation APIs.

4. Template Parameters: CloudFormation templates can include parameters that allow you to customize the stack’s behavior when creating or updating it. Parameters enable you to provide input values at runtime, making your templates more flexible and reusable.

5. Resource Dependencies: CloudFormation automatically manages resource dependencies based on the relationships defined in your template. It determines the order in which resources need to be created or updated to ensure that dependencies are met.

6. Change Sets: Before applying changes to a stack, CloudFormation allows you to preview the proposed changes using change sets. Change sets provide a summary of the modifications that will be applied to the stack, allowing you to review and approve them before executing the changes.

7. Stack Policies: Stack policies allow you to control updates to specific resources within a stack. You can use stack policies to prevent accidental modifications or enforce stricter control over resource updates.

8. Integration: CloudFormation integrates with other AWS services, allowing you to provision and manage a wide range of resources. It supports the entire AWS resource ecosystem, including EC2 instances, RDS databases, VPCs, security groups, IAM roles, and more.