Regsvr32 is a command-line utility that registers and unregisters DLL (Dynamic Link Library) and OCX (ActiveX Control) files in the Windows Registry. The key thing to understand is that it doesn't physically move files - it simply creates registry entries pointing to the DLL's current location.

Contrary to common misconception, you don't need to place DLLs in System32 before registration. The registration process works from any location, but consider these technical implications:

regsvr32 "C:\Users\Admin\Desktop\mylibrary.dll"

The registry entries will contain the full path to your desktop location. This becomes problematic if:

• You move or delete the original DLL
• Other applications expect System32 as the standard location
• Permissions differ between locations

When you execute regsvr32, it:

1. Loads the DLL into memory
2. Calls its DllRegisterServer exported function
3. Creates registry entries under HKEY_CLASSES_ROOT
4. Unloads the DLL

Here's a sample C++ implementation you might find in a DLL:

STDAPI DllRegisterServer()
{
    // Create registry entries
    RegCreateKeyEx(HKEY_CLASSES_ROOT, "MyLibrary.Component", 
        0, NULL, REG_OPTION_NON_VOLATILE, KEY_WRITE, NULL, &hKey, NULL);
    
    // Set CLSID and other values
    RegSetValueEx(hKey, "CLSID", 0, REG_SZ, 
        (const BYTE*)"{12345678-ABCD-EFGH-IJKL-MNOPQRSTUVWX}", 
        sizeof("{12345678-ABCD-EFGH-IJKL-MNOPQRSTUVWX}"));
        
    return S_OK;
}

For server deployments:

• Use a standard location (System32 or a dedicated application folder)
• Maintain consistent paths between development and production
• Consider using Windows Installer (MSI) packages for proper registration

After registration, if you delete the original DLL:

• Applications will fail when trying to load the component
• Error messages like "The specified module could not be found" will appear
• The system becomes unstable if critical system DLLs are removed

To properly clean up:

regsvr32 /u "C:\path\to\your.dll"

This calls the DLL's DllUnregisterServer function to remove registry entries.

The regsvr32.exe utility is a Windows command-line tool that registers and unregisters OLE controls (DLL or OCX files) in the registry. When you execute:

regsvr32 path\to\your.dll

The process performs these technical steps:

1. Loads the DLL into memory using LoadLibrary()
2. Calls the DLL's DllRegisterServer export function
3. Unloads the library if registration succeeds

Contrary to common belief, you don't need to place DLLs in System32 before registration. The registry stores the full path used during registration. Here's what happens in different scenarios:

// Registering from desktop (works but not recommended)
regsvr32 C:\Users\Admin\Desktop\example.dll

// Registering from System32 (traditional approach)
regsvr32 C:\Windows\System32\example.dll

After registration, you cannot delete the DLL file. The registry points to the original file location, and Windows will need to access it when:

• The COM object is instantiated
• Applications query the registry for the CLSID
• System performs dependency checks

For server deployments, follow this pattern:

@echo off
set DLL_NAME=example.dll
set TARGET_DIR=%SystemRoot%\System32

:: Copy with version check
if exist "%TARGET_DIR%\%DLL_NAME%" (
    fc /b "%DLL_NAME%" "%TARGET_DIR%\%DLL_NAME%" >nul
    if errorlevel 1 (
        echo Updating existing DLL...
        takeown /f "%TARGET_DIR%\%DLL_NAME%"
        icacls "%TARGET_DIR%\%DLL_NAME%" /grant administrators:F
        copy /y "%DLL_NAME%" "%TARGET_DIR%\"
    )
) else (
    copy "%DLL_NAME%" "%TARGET_DIR%\"
)

:: Register with error handling
regsvr32 /s "%TARGET_DIR%\%DLL_NAME%"
if errorlevel 1 (
    echo Registration failed with error %ERRORLEVEL%
    exit /b %ERRORLEVEL%
)

If you encounter problems:

:: Check if DLL exports registration functions
dumpbin /exports example.dll | find "DllRegisterServer"

:: Verify registry entries (replace CLSID with actual value)
reg query HKCR\CLSID\{YOUR-CLSID-GUID}\InprocServer32

Remember that 64-bit systems have separate registration requirements - use %windir%\SysWoW64\regsvr32.exe for 32-bit DLLs on 64-bit Windows.