The Registry comprises a number of logical sections, or "hives". Hives are generally named by their Windows API definitions, which all begin "HKEY". They are frequently abbreviated to a three- or four-letter short name starting with "HK" (e.g. HKCU and HKLM). Technically, they are predefined handles (with known constant values) to specific keys that are either maintained in memory, or stored in hive files stored in the local filesystem and loaded by the system kernel at boot time and then shared (with various access rights) between all processes running on the local system, or loaded and mapped in all processes started in a user session when the user logs on the system.
How to add a reg key
Just double click on it and it will ask you to confirm the operation and click
Ok it will be added in the registry file on OS. Or open the registry editor through run command and click on
File> Import and then you can add the
Hive files are not accessible directly while you can run the registry file. Hive can be added through only the
When you will try to import a hive it will completely restore the keys under it which you have backed up. While only a single
.reg key will affect the only under the hive to that particular place(key) which it belongs.