Online help for Microsoft Windows - most commands will give help when
run with COMMAND /? or COMMAND -?
Help will not detect if Command Extensions have disabled and will print help messages assuming the extensions are available.
GUI Help files (WINHELP and WINHLP32.exe) are no longer supported in Windows 10 and will redirect to online help.
Equivalent PowerShell: Get-Help - Open the help file.
Equivalent bash command (Linux): man pages.