Shimming is a technique used in Windows to enhance compatibility and performance of applications. It involves making adjustments or modifications to the behavior of an application without changing its source code. Shimming is particularly important for Windows users as it allows them to run legacy applications on newer versions of the operating system and improves overall system performance.

Shimming in Windows is achieved through the use of Application Compatibility Toolkit (ACT) and the Compatibility Administrator tool. These tools allow users to create custom compatibility fixes, known as shims, which can be applied to specific applications. Shims can address a variety of compatibility issues, such as resolving conflicts with newer versions of Windows libraries, redirecting file and registry accesses, and enabling compatibility modes.

Examples:

1. Redirecting File Access: Suppose you have an application that tries to write to a system-protected directory, which is not allowed in newer versions of Windows. By creating a shim, you can redirect the file access to a user-writable directory, allowing the application to function properly.

2. Enabling Compatibility Mode: Let's say you have an older application that was designed for Windows XP and does not work correctly on Windows 10. By creating a shim and enabling compatibility mode, you can replicate the behavior of Windows XP, making the application work as intended.

3. Fixing Registry Access: If an application tries to access a registry key that has been moved or renamed in a newer version of Windows, you can create a shim to redirect the registry access to the correct location.