When moving to a new Windows system, either after getting a new computer or reinstalling Windows, you may be tempted to copy a program's folder to your new system just like you'd copy your files. But this normally won't work.

Some programs — games especially — do allow you to copy their folders over and run the program. Other programs specifically designed to be "portable apps" will also be able to do this.

Why Do Programs Require Installation?

When you install a program on Windows, it appears to only install to a specific folder, generally under Program Files. For example, Apple's iTunes software installs to C:Program Files (x86)>iTunes by default.

In a simpler world, you could copy the iTunes folder to a new computer and run iTunes from the folder without any additional work. However, it isn't this simple. Programs actually scatter their data all over the place:

  • Registry Settings: Many programs save settings in the Windows registry. These settings may be scattered all over the Windows registry — for example, there may be several registry keys for program settings, other registry keys for context menu options, and keys that make the program the default program for certain files. If any of these registry keys aren't present, the program may display errors when you try to run it.
  • Other Program Folders: Certain programs also install other software that they require. For example, iTunes installs the Apple Application Support application, among others. If Apple Application Support isn't present on your computer, iTunes won't run. Apple Application support installs to its own folder and has its own registry settings, like any other program.
  • Windows System Files: Some programs dump DLL files and other files into the Windows system directory and won't run if these files aren't present.
  • System Services: Many programs install Windows services that they require. For example, Adobe Flash Player installs an Adobe Flash Player Update service. While you could copy the Adobe Flash plugin files to a new system, you wouldn't have the update service and you'd have to manually update Adobe Flash. Installing Adobe Flash with the installer would ensure that the updater service is present. Some programs may not even run without these services available.
  • Hardware Locking: A few programs may use DRM that ties the program to a specific computer's hardware. They may refuse to run when you copy their files to a new computer.
  • User Data Folders: Most modern programs don't save their settings to their program folder. Whatever they don't store in the registry is likely stored in each user's Application Data folder. Even if you could copy the program's files over, these settings would have to be copied or you'd lose your programs' settings and data.

Theoretically, it would be possible to locate everything — registry settings, program files, system files, user data folders — and copy them to the new computer, reinstalling any system services and putting everything in the exact same place. However, this would be extremely tedious and would often require using some sort of program that monitors the changes an installer makes. In practice, simply reinstalling the program is much faster and easier. The installer will set up everything the program needs on your system.

When You Can Copy Programs Over

Some programs are designed to be portable, not writing to the registry, storing their data in their own folder, and running from an .exe file without any installation required. These programs are the exception rather than the rule, but they do exist.

RELATED: 5 Tips and Tricks to Get the Most Out of Steam

  • Games: Many PC games are very large and would require gigabytes and gigabytes of downloading on a new computer. To save bandwidth and speed things up, some game developers have made their game folders portable. For example, Valve's Steam service allows you to copy your Steam program folder to a new computer, then double-click the Steam.exe file inside to get back up and running without a reinstall. Blizzard's games — Starcraft II, Diablo III, World of Warcraft — all work the same way, allowing you to copy the game's folder and double-click its .exe to run it on a new computer. Other games may or may not work the same way — that's up to the developer.

RELATED: The Best Free Portable Apps for Your Flash Drive Toolkit

  • Portable Applications: Some applications are specially packaged as portable applications, allowing you to take them with you everywhere on a USB stick or in your Dropbox folder. Just double-click the program's .exe file and it will run on a computer, saving its data to its own private folder and not requiring any installation. If you constantly move between computes or reinstall Windows, you may want to look at using portable applications to make your life easier.

How to Quickly Reinstall Desktop Programs

RELATED: 4 Ways to Quickly Install Your Desktop Programs After Getting a New Computer or Reinstalling Windows

You'll have to reinstall most of your desktop programs rather than just copy their files over when you get a new computer, reinstall Windows, or even just use the Refresh Your PC feature in Windows 8, which wipes out your installed desktop programs.

Luckily, there are several ways to quickly install your favorite desktop applications. These programs help speed up the installation process, saving you the trouble of downloading files from many different websites and clicking through installation wizards.

The Windows Store had a chance to make reinstalling desktop apps easy on Windows 8, but Microsoft only allows Modern apps to be downloaded and updated through the Windows Store.

If the desktop goes away and everyone starts using Modern apps, this won't be a problem because Modern apps are automatically synced between Windows PCs as of Windows 8.1.

The above article may contain affiliate links, which help support How-To Geek.