This topic introduces the terms related with Resource Orchestration Service (ROS).

Term Description
template A JSON or YAML file encoded in UTF-8. You can save template files with extensions such as .json, .yaml, .template or .txt. Templates are used to create stacks and serve as the blueprint for the underlying infrastructure and architecture. They define the configurations and dependencies of Alibaba Cloud resources.
stack A collection of ROS resources that you can manage as a single unit. You can create, update, or delete a stack to create, update, or delete a collection of resources.
stack group A collection of ROS stacks that you can manage as a single unit. A stack group allows you to use a single ROS template to create stacks across multiple Alibaba Cloud accounts and regions. All resources included in each stack are defined by the ROS template of the stack group.
change set A feature that is used to update running stacks and serves as a summary of proposed changes. You can preview the impacts that specific changes to a stack will have on the running resources. ROS modifies your stacks only if you execute change sets.
drift detection A feature that is used to detect whether the actual configuration of stack resources differs, or have drifted, from the expected configuration. You can then take corrective measures to resynchronize resources with their template definitions. Drift correction helps ensure that changes in resources can be identified and that relevant actions can be taken.
tag A key-value pair that can be used to label and classify ROS stacks or templates.