Core HCM and Platform Configuration
Organizations are the skeleton
Workday's core HCM model rests on three layers: organizations (company hierarchy, supervisory organizations, cost centers, locations, custom organizations), job architecture (job families, job profiles, job requisitions), and worker records (pre-hire, employee, contingent worker, terminated).
Supervisory organizations drive most people-data rollups: headcount, approval routing, and manager self-service. A worker has one primary supervisory organization assignment plus any number of additional ones; hierarchy-based reporting and routing generally follow the primary assignment, so a question about who approves a hire usually resolves to the primary sup org's manager. Position management is a tenant-level setting: when it is on, each worker sits in a position that carries its own job profile, location, and headcount, and hiring requires an open position. When it is off, jobs attach directly to the worker.
Effective dating and actions
Nearly every worker attribute is effective-dated, and changes are made through business process actions: Hire, Add Job, Change Job, Termination, Change Compensation. Change Job is the action for transfers, promotions, and job changes; terminating and rehiring destroys continuity and is almost always the wrong answer.
Trap: options that offer to edit the worker record directly. Worker data flows through business processes; direct edits exist only for a narrow set of fields.
Rule of thumb: if a question asks what history looks like, read it 'as of' a date and assume retroactive changes are permitted but audited. Prefer delivered configuration objects (job profiles, organization types) over creating duplicates.