see also: SMB
Every disk volume on the system is shared administrative share. These are named in the form driveletter$, e.g. C$, D$ and so on. Access them with \\computername\c$.
From Windows 8.1 onwards, Microsoft disabled these for security reasons. Enable them with setting the DWORD registry key LocalAccountTokenFilterPolicy in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\ to 1. (source)
Is used for name resolution in Windows networks. Case insensitive like NTFS defaults.