Shared library

A shared library is a library of executable code that is loaded in memory such that multiple executables (programs and other libraries) can use it at runtime.

In contrast, a static library is copied into an executable. A static library can be re-used (a form of sharing) in multiple executables, but each executable contains a copy of the library code instead of sharing a copy in memory with other executables. Although not true today, historically, all libraries were static. Although a shared library can have static linkage, such a library is not classified as a static library.

Often, a shared library is also a dynamic library loaded by a dynamic linker, which generally makes use of the library easier for the programmer than if it instead it had static linkage. A dynamic library need not be accessible to multiple executables (shared library) and a shared library need not be loaded at consumer runtime (dynamic library).