Different users, programs, services or remote systems may only see some parts of the hierarchy or distinct hierarchies from the same root keys.
Registry values are name/data pairs stored within keys.
The HKEY_LOCAL_MACHINE (local machine-specific configuration data) and HKEY_CURRENT_USER (user-specific configuration data) nodes have a similar structure to each other; user applications typically look up their settings by first checking for them in "HKEY_CURRENT_USER\Software\Vendor's name\Application's name\Version\Setting name", and if the setting is not found, look instead in the same location under the HKEY_LOCAL_MACHINE key.
However, the converse may apply for administrator-enforced policy settings where HKLM may take precedence over HKCU.
Registry values are non-container objects similar to files. Keys are referenced with a syntax similar to Windows' path names, using backslashes to indicate levels of hierarchy.