List of Environment Variables in Windows Operating System

Windows XP Environment Variables

Environment Variable	Path
%ALLUSERSPROFILE%	C:\Documents and Settings\All Users
%APPDATA%	C:\Documents and Settings{username}\Application Data
%COMMONPROGRAMFILES%	C:\Program Files\Common Files
%COMMONPROGRAMFILES(x86)%	C:\Program Files (x86)\Common Files
%COMSPEC%	C:\Windows\System32\cmd.exe
%HOMEDRIVE%	C:
%HOMEPATH%	C:\Documents and Settings{username}
%PROGRAMFILES%	C:\Program Files
%PROGRAMFILES(X86)%	C:\Program Files (x86) (only in 64-bit version)
%SystemDrive%	C:
%SystemRoot%	C:\Windows
%TEMP% and %TMP%	C:\Documents and Settings{username}\Local Settings\Temp
%USERPROFILE%	C:\Documents and Settings{username}
%WINDIR%	C:\Windows

Windows Vista and Later

Environment Variable	Path
%ALLUSERSPROFILE%	C:\ProgramData
%APPDATA%	C:\Users{username}\AppData\Roaming
%COMMONPROGRAMFILES%	C:\Program Files\Common Files
%COMMONPROGRAMFILES(x86)%	C:\Program Files (x86)\Common Files
%COMSPEC%	C:\Windows\System32\cmd.exe
%HOMEDRIVE%	C:
%HOMEPATH%	C:\Users{username}
%LOCALAPPDATA%	C:\Users{username}\AppData\Local
%PROGRAMDATA%	C:\ProgramData
%PROGRAMFILES%	C:\Program Files
%PROGRAMFILES(X86)%	C:\Program Files (x86) (only in 64-bit version)
%PUBLIC%	C:\Users\Public
%SystemDrive%	C:
%SystemRoot%	C:\Windows
%TEMP% and %TMP%	C:\Users{username}\AppData\Local\Temp
%USERPROFILE%	C:\Users{username}
%WINDIR%	C:\Windows
%SystemDirectory%	C:\WINDOWS\System32

More

Environment Variable	Detail
%CD%	The current directory.
%ERRORLEVEL%	A number defining exit status of a previous command or called executable.
%OS%	The operating system the user is running
%USERDOMAIN%	The name of the domain that contains the user's account
%USERNAME%	The user's name
%DATE%	Current date in the format
%TIME%	Current time in the format
%RANDOM%	A random number between 0 and 32767.