These categories deal with the STL or Standard Template Library, therefore only submit sites that are related to the STL in general. There are subcategories provided for tutorials, books and articles about STL.
STL or Standard Template Library is a set of template classes that are contained as integral part of the current C++ Standard.
The Standard describes in detail a set of containers, iterators and other functionality that implementations of the STL need to provide.
There are already a few implementations available, some free, some commercial. More and more developers are using the STL because a lot of basic work is already done, tested and proved with nearly optimal performance and can be reused over and over again.