Description of the Windows 2000 Registry

The Windows 2000 registry is a hierarchical database that contains the value of variables in Windows 2000 and in the applications and services that run on Windows 2000. The operating system and other programs also store data about users, and about the current configuration of the system and its components in the registry. Because the registry is available whenever the system is running, programs that start and stop can keep persistent data in the registry.

caution-icon Caution

Do not use a registry editor to edit the registry directly unless you have no alternative. The registry editors bypass the standard safeguards provided by administrative tools. These safeguards prevent you from entering conflicting settings or settings that are likely to degrade performance or damage your system. Editing the registry directly can have serious, unexpected consequences that can prevent the system from starting and require that you reinstall Windows 2000. To configure or customize Windows 2000, use the programs in Microsoft Management Console or Control Panel whenever possible.

Structure of the Registry

Much of the registry consists of nested containers known as subtrees, keys, and subkeys. These are like folders. The data actually is stored in the registry entries, the lowest level element in the registry. The entries are like files. The series of nested containers comprise a path to each entry. Because entry names are unique only within a path, entries are referenced by their full registry path and name.

An entry consists of a name, a data type, which defines the length and format of data that the entry can store, and a a field known as the value of a registry entry. Data is stored in value.

Variability of the Registry

No two registries are exactly alike. Because the registry stores data about the hardware and software installed on and available to your computer, much of the registry is very specific to the computer and its current configuration.

Also, some of the registry content is constant, but other content is created anew each time you start the operating system or log on as a user. As a result, many changes to the registry are deleted or replaced when you restart or log off and log on again.

Finally, the location of registry entries can change. Programmers sometimes move entries when they update programs and features, and programs have been known to move entire sections of the registry to a new location when a service or feature is enabled.

As a result, it is not prudent to include a direct reference to a registry entry path and name in any program or script. If you do, the program or script might not operate correctly with future versions of the operating system. To retrieve, add, delete, or change a registry entries, use the standard Win32 APIs. The APIs are updated with each version of the system to find the data you need.

How Registry Data is Used

Programs store all types of data in registry entries. Typically, programs use standard Win32 application programning interfaces (APIs) to retrieve data from the registry. The program specifies an entry by its path and name and the API returns the value of the entry. Programs also use standard APIs to add and delete registry content and to change the values of registry entries.

After they retrieve and read the data in the value of an entry, each program interprets the data and implements its result independently, depending on how the program is written.

For example, a value of 1 might indicate to a program that an optional feature is enabled or disabled, or it might force the program to wait for one millisecond or one day before taking action.

A file location stored in a registry entry might tell the program where to find a file or it might instruct the program to move the file to the specified location.

Because programs are so infinitely variable, it is very difficult to predict how they interpret the registry data. It is important to remember that the registry belongs to programs, not to users. And, unless you are very familiar with the program or the registry entry, it is wise to stay out of the registry.

Users and the Registry

Most users never need to view or edit the registry. The administrative tools and Windows interface enable users to change set preferences and change the services and features of the operating system safely.

However, there are rare instances when an operating system variable cannot be changed by any means other than editing the registry.

If this occurs, consult this file and other resources to make certain that you must edit the registry. Then, back up the registry using standard procedures. Make your changes and test them before returning your computer to its place in your enterprise.