What controls the publishing and retiring process for knowledge articles?

Approval Policies are specific configurations for approvals, which are components within a workflow, not the overarching control mechanism.

Approval Definitions are configurations for specific approval processes, which are part of a workflow, rather than controlling the entire article lifecycle.

The Workflow Designer is the tool used within ServiceNow to create, modify, and manage workflows, which automate and control the lifecycle stages, including publishing and retiring, for knowledge articles.

While 'Workflows' are the actual processes, the 'Workflow Designer' is the specific tool that controls their creation and management.

The 'State Lifecycle' describes the different stages an article goes through, but it is the workflow that controls the transitions between these states.