AWS CloudFormation Concepts
External
Internal
Overview
CloudFormation creates and configures resources, grouped in stacks.
Stack
A stack is a collection of AWS resources that can be managed (create, update or delete) as a single unit. All resources in a stack are defined by the stack's AWS CloudFormation template. Because AWS CloudFormation treats the stack resources as a single unit, they must all be created or deleted successfully for the stack to be created or deleted. If a resource cannot be created, AWS CloudFormation rolls the stack back and automatically deletes any resources that were created. If a resource cannot be deleted, any remaining resources are retained until the stack can be successfully deleted.
Nested Stack
A nested stack is a stack created as part of other stacks.
Template
A template is a declaration of AWS resources that make up a stack. The templates are stored as JSON or YAML text files.