The C++ standard library type list represents a doubly-linked list, and forward_list is a singly-linked list. Fortunately, the implementations of both of these lists are pretty much what you expect.

Inside STL: The lists

By Raymond Chen

From the article:

Let’s start with the simpler forward_list.

template<typename T>
struct forward_list
{
    forward_list_node<T>* head;
};

template<typename T>
struct forward_list_node
{
    forward_list_node<T>* next;
    T value;
};

The forward_list itself is a pointer to the first element of the list, or nullptr if the list is empty. Each subsequent element contains a pointer to the next element, or nullptr if there is no next element.