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Registry Structure

The Windows registry is a hierarchical database. Understanding its structure makes editing safer and faster.

Keys And Values​

A key is a container, comparable to a folder. A key can hold values and further subkeys. Every value belongs to exactly one key.

  • A key organizes the hierarchy and can be assigned one or more values.
  • A value stores actual data — a piece of text, a number, or binary content — under a name inside a key.

Each key also has one unnamed default value, shown in the value list as (Default).

Key vs. value

If you are looking for the folder-like structure on the left, that is the key tree. The named entries with data on the right are values. You create, edit, and delete them separately.

The Main Keys​

At the top of the tree are five main keys (also called root keys or hives). Every path in the registry begins with one of them:

Main keyAbbreviationContains
HKEY_CLASSES_ROOTHKCRFile type associations and COM/class registration.
HKEY_CURRENT_USERHKCUSettings for the user who is currently signed in.
HKEY_LOCAL_MACHINEHKLMSystem-wide settings for the whole computer.
HKEY_USERSHKUSettings for all user profiles on the computer.
HKEY_CURRENT_CONFIGHKCCThe current hardware configuration profile.

Below the main keys are many subkeys, which in turn can contain further subkeys and values.

Paths​

A registry path is written as a chain of key names separated by backslashes, starting from a main key — for example:

HKEY_CURRENT_USER\Software\O&O\O&O RegEditor

O&O RegEditor also accepts paths copied from the Windows Registry Editor that begin with Computer\ (or the localized My Computer\). The leading Computer\ part is removed automatically. See Browsing And Navigation.

Editing Safely​

Because so much of Windows depends on the registry, keep these principles in mind:

  • Export the key you are about to change before you change it.
  • Change one thing at a time and note what you changed.
  • Prefer to edit keys under HKEY_CURRENT_USER for user-specific settings; changes under HKEY_LOCAL_MACHINE affect every user and require administrator rights.