Windows Inside & Out · Windows Under the Hood · Lesson 1 of 5

The Registry

Peek inside Windows' settings database, and learn why to leave it alone.

Inside the Registry Editor

Windows has to remember thousands of choices. Your wallpaper, your mouse speed, which app opens your photos. It keeps most of them in one place.

The registry is Windows' settings database. A database is an organized store of information. Windows and many apps read the registry every time they start.

The registry is arranged like folders inside folders. A key is like a folder. A value is one setting inside a key, like a file inside a folder. Each value has a name and some data, such as a number or a file location.

The biggest top folders are called hives, and the two you'll see most are HKEY_CURRENT_USER, for your own settings, and HKEY_LOCAL_MACHINE, for settings that cover the whole computer.

You can look inside with Registry Editor. Select Start, type regedit, and choose Registry Editor. Windows asks if you want to allow this app to make changes to your device. That question is a hint that this tool is powerful.

Looking is safe. Changing is not. Registry Editor has no Undo button, and every change saves right away. One wrong change can stop an app, or even Windows, from starting properly.

On a Mac, there's no registry. Apps keep their settings in small preference files instead, and you change them in System Settings or in each app.

On the practice computer, open HKEY_CURRENT_USER > Control Panel > Desktop and find the wallpaper setting. Then try to delete a key and read the warning.

Registry advice and backups

Search for almost any Windows problem and you'll find advice like "just change this registry value." Some of it is good. A lot of it is old, wrong, or written for a different version of Windows.

Here is why random registry advice is risky:

• There is no Undo. A typo can change the wrong setting.
• Tips from years ago may do nothing today, or cause new problems.
• A downloaded .reg file changes many registry values at once when you open it. You can't easily see what it changes.
• "Registry cleaner" apps promise a faster computer. Microsoft doesn't support them, and they can cause real harm.

Most everyday settings are already in Settings or in an app's own menus. Use those first. They're safer because they only offer choices that work.

If a trusted source, like Microsoft Support or your workplace's IT team, tells you to edit the registry, back up first. You have two good options:

1. Create a restore point, a saved snapshot of Windows settings you can go back to. Type "restore point" in Start search to find it.
2. In Registry Editor, select the key you'll change, then choose File > Export. This saves a copy of that key as a .reg file. If something goes wrong, File > Import puts it back.

Then follow the steps exactly, one at a time. Change only what the guide names. Restart if it tells you to.

A good rule: if you don't know what a change does, or who wrote the advice, leave the registry alone.