DLL Files

A Dynamic Link Library (DLL) is a file of code containing functions that can be called from other executable code (either an application or another DLL). Programmers use DLLs to provide code that they can reuse and to parcel out distinct jobs. Unlike an executable (EXE) file, a DLL cannot be directly run. DLLs must be called from other code that is already executing.

In more understandable words, a DLL is a file which does a particular job, and allows other programs to use its efforts in assisting the program's job. Some programs use a DLL so that they won't need to spend time figuring out how to do that job. For example, Microsoft has a DLL comctl32.dll which does all the user interface jobs (toolbars, text boxes, scroll bars, etc). So, other programs use that DLL so they won't have to create their own edit boxes, etc. When a program requires a DLL to run, and can't find it, it won't be able to run because its suddenly missing the DLL to perform some of its critical work. We've all used DLLs before and we're using them now. They're required to run all Windows programs, including Windows but you never actually see them at work. There are different versions of the same file name. Just because the file appears to be the same doesn't mean it is. To check what version the file is, open Windows Explorer, locate the file and right click on it. Select Properties and click on the Version tab If there is no version tab then the file does not have a version number. Generally, if you have a newer version of a file, don't replace it with an older version.