From Worms Knowledge Base
Overview The Windows registry is a database which stores settings and options for the operating system for Microsoft Windows 32-bit versions, 64-bit versions and Windows Mobile. It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to "Control Panel" settings, or file associations, system policies, or installed software, the changes are reflected and stored in the registry.
The Registry is split into a number of logical sections. These are generally known by the names of the definitions used to access them in the Windows API, which all begin "HKEY" (an abbreviation for "Hive Key"); often, they are abbreviated to a three- or four-letter short name starting with "HK".
Each of these keys is divided into subkeys, which may contain further subkeys, and so on. Any key may contain values. These values can be:
- String Value
- Binary Value (0 and 1's)
- DWORD Value (numbers between 0 and 4,294,967,295 [232 – 1])
- Multi-String value
- Expandable String Value
Each key has a default value, which is in effect a value with the same name as the key. Registry keys and values are specified with a syntax similar to Windows' filenames, using backslashes to indicate levels of hierarchy. E.g. HKEY_LOCAL_MACHINE\Software\Microsoft\Windows refers to the subkey "Windows" of the subkey "Microsoft" of the subkey "Software" of the HKEY_LOCAL_MACHINE key.