Windows locates a DLL by searching the same directories it searches to find an application module. To be found by Windows, the DLL must be in one of the following directories:
1.The current directory
2.The Windows directory (the directory containing WIN.COM); the GetWindowsDirectory function obtains the pathname of this directory
3.The Windows system directory (the directory containing such system files as KERNEL.EXE); the GetSystemDirectory function obtains the pathname of this directory
4.Any of the directories listed in the PATH environment variable
5.Any directory in the list of directories mapped in a network
Windows searches the directories in the listed order.
Implicitly loaded libraries must be named with the .DLL extension.
This section explained what a DLL does in the context of the Windows environment. The next section explains what a custom DLL can do for your application.