Terminology

The Temporal server implements abstractions such as Workflow, Activity, and Scheduler.
Each of these abstractions is an Archetype.
An instance of an Archetype is an Execution (e.g. a workflow execution, an activity execution).
An execution possesses a BusinessID that should typically be meaningful in the user’s own systems. It is guaranteed to be unique among executions within a namespace that are in a non-terminal state.
A single Execution may consist of multiple non-overlapping runs (e.g. successive non-overlapping invocations of an Activity or Workflow that share the same businessID, successive non-overlapping invocations of a Workflow by a Scheduler).
An Execution has a tree structure in which each subtree is a Component. A component, and thus an execution, may be a tree comprising one node only.
A ComponentRef contains an ExecutionKey, a ComponentPath, and additional information identifying (uniquely across all clusters when there is a multi-cluster configuration with failovers) a specific transition in execution history. Together these identify a component within an execution.