Search notes:

%SystemRoot%

A typical value for the environment variable %SystemRoot% seems to be C:\Windows. %windir% is another environment variable that also points to this location.

Among others(?), this (and its subdirectories?) store so-called System apps which are integral to the Windows Operating System. See also types of apps in Windows 10.

%SystemRoot% is also found in the registry as value of Directory under the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows.

The value of %SystemRoot% can be queried with

wmic os get WindowsDirectory

Opening folders below %SYTEMROOT%

Folder below %SYTEMROOT% can be opend in cmd.exe with start (if %SystemRoot% is in %PATH% which it usually is). The following example opens the fonts folder below C:\windows

C:\> start fonts

Similarly, these folders can also be directly opened using Win+R and then typing the folder name.

Relationship between %SystemRoot% and %windir%

%windir% is supposed to the same directory as %SystemRoot%.

The difference between these is that %SystemRoot% is not a real environment variable but is kind of hardcoded into the kernel while %windir% is an ordinary whose value is set in the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment and usually assigned the value of %SystemRoot%.

The value of %SystemRoot% is determined when Windows is installed.

Allegedly, in Windows 10, the environment variable %CSIDL_WINDOWS% also points to %SystemRoot%. However, I found that not to be the case.

Some files

bfsvc.exe	Boot File Servicing Utility
bootstat.dat
DtcInstall.log
explorer.exe	Windows Explorer
HelpPane.exe	Microsoft Help and Support
hh.exe	Microsoft® HTML Help Executable
lsasetup.log
mib.bin
notepad.exe	Notepad
PFRO.log
Professional.xml
regedit.exe	GUI based registry editor.
setuperr.log
splwow64.exe	Print driver host for applications
system.ini
twain_32.dll	Twain_32 Source Manager (Image Acquisition Interface)
win.ini
WindowsUpdate.log
winhlp32.exe	Windows Winhlp32 Stub
WMSysPr9.prx
write.exe	Windows Write

Some subdirectories of %windir% might be:

Showing the «System Root» with bcdedit

The value of the System Root shows up, for example, when displaying boot options with bcdedit.exe:

C:\> bcdedit.exe /enum
…
Windows Boot Loader
-------------------
…
osdevice                partition=C:
systemroot              \WINDOWS

TODO

Compare with the values PathName and SystemRoot under KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion.