How is the Windows registry structured?

The registry database is stored in a hierarchical structure. Depending on your Windows version, the registry comprises four to six sub-trees of keys called hives (also referred to as discrete files).

Each hive contains a registry sub-tree, which has a key that serves as the root (ie, starting point) of the tree. A registry hive is a group of keys, sub keys, and values in the registry that has a set of supporting files containing backups of its data. Sub keys, and their values, reside beneath the root. The values contain the actual information stored in the registry.

The majority of the information in the registry is placed there automatically, by Windows, when the operating system is installed. The rest comes from applications and hardware via installation routines. It is also possible, but not necessarily advisable, to edit registry data manually using the Registry Editor (type 'regedit.exe' at the Start Menu > Run prompt).