First thing first, Wiki: 

• http://en.wikipedia.org/wiki/Dynamic-link_library
• http://en.wikipedia.org/wiki/Static_library

On Windows, SLL‘s file extension is .lib (or .a), DLL‘s file extension is .dll

On Linux, is .a and .so (shared object).

• http://www.cnblogs.com/ardar/articles/357321.html

c++ about SLL(Static-Link Library) and DLL(Dynamic-Link Library)