DLL and LIB files - what and why?

Question

I know very little about DLL\'s and LIB\'s other than that they contain vital code required for a program to run properly - libraries. But why do compilers generate them at

Answer 1

One important reason for creating a DLL/LIB rather than just compiling the code into an executable is reuse and relocation. The average Java or .NET application (for example) will most likely use several 3rd party (or framework) libraries. It is much easier and faster to just compile against a pre-built library, rather than having to compile all of the 3rd party code into your application. Compiling your code into libraries also encourages good design practices, e.g. designing your classes to be used in different types of applications.