C++ defines a Standard Template Library (STL). All the major compiler vendors now offer the STL as part of their compiler. The STL is a library of template-based container classes, including vectors, lists, queues, and stacks. The STL also includes a number of common algorithms, including sorting and searching.
The goal of the STL is to give you an alternative to reinventing the wheel for these common requirements. The STL is tested and debugged, offers high performance, and it's free! Most important, the STL is reusable; when you understand how to use an STL container, you can use it in all your programs without reinventing it.