Defined in header
std::forward_list is a container that supports fast insertion and removal of elements from anywhere in the container. Fast random access is not supported. It is implemented as singly-linked list and essentially does not have any overhead compared to its implementation in C. Compared to std::list this container provides more space efficient storage when bidirectional iteration is not needed.
Addition, removal and moving the elements within the list or across several lists does not invalidate the iterators. An iterator is invalidated only when the corresponding element is deleted.