Open Group Policy Management Editor on a domain controller, then open it on a freshly-imaged Windows 10 admin workstation, and you can see different settings in the same Administrative Templates…
The conceptual reference for Group Policy: what GPOs actually are, the difference between local and domain GPOs, the two built-in defaults (Default Domain Policy and Default Domain Controllers Policy) and why you should not modify them for general settings, the Computer-Configuration vs User-Configuration split, what GPOs can and cannot be linked to (sites/domains/OUs yes; individual user/computer accounts no), administrative templates (ADMX = engine, ADML = dashboard labels), GPO scope (link + Security Filtering + WMI Filtering + Item-Level Targeting for Preferences), and the LSDOU processing order with last-write semantics. Walks inheritance / Block Inheritance / Enforced precedence (Enforced beats Block), the GUI tools (gpmc.msc, gpedit.msc) and CLI tools (gpupdate, gpresult, LGPO.exe, the GroupPolicy PowerShell module), every GPO attribute (Name, GUID, Links, Security Filtering, WMI Filtering, Version Number, Enabled/Disabled state), and the Azure AD DS differences (no site links, no software deployment, predefined OUs, AAD DC Administrators group). Includes seven best practices and cross-links to the practical articles in the pathway.
GPOs can be deleted in two clicks; AD replicates the deletion to every DC, SYSVOL files vanish, and clients drop the policy at next refresh. AD Recycle Bin restores the container in AD but not the SYSVOL GPT files where the actual policy settings live - so per-GPO backup is its own discipline. Walks the full GPMC lifecycle: Back Up All... for a fleet snapshot, Back Up... for one GPO before a risky edit, Manage Backups... for preview-then-restore (View Settings opens an HTML report, Restore overwrites the live GPO), and the manual re-link step that the backup does NOT capture. Plus the PowerShell-only equivalent (Backup-GPO -All / Restore-GPO -Name) for scheduled / scripted use. Includes the four pitfalls (no description = uninformative Manage Backups list, backup-on-the-DC-fails-with-the-DC trap, untested-backup wishful thinking, View-Settings-first habit) and the link-map documentation gotcha.
