User roles are the organization-wide dictionary of access levels a user can hold — the categories themselves, not the per-user assignments. Each role has a role_type of job_admin or site_admin and a display name; built-in roles ship as Standard, Private, and Site Admin, and customers may configure additional job_admin roles through the Greenhouse admin UI. The id returned here is the user_role_id used when assigning a user to a job through user_job_permissions (per-job grant) or future_job_permissions (office/department-scoped grant for jobs created later).