The Standard Template Library (STL) is a collection of data structures and algorithms that establish uniform ANSI/ISO standards for portable extensions to the basic C++ language. Microsoft's Visual C++ includes STL, but it also gives you the option of working with the Microsoft Foundation Class Library (MFC). Unlike MFC, STL is not tied to any specific platform, and a compatible version of STL exists for virtually every major C++ compiler.
The Standard Template Library (STL) is a software library included in the C++ Standard Library. It provides containers, iterators, and algorithms. More specifically, the C++ Standard Library is based on the STL published by SGI.