On which container are stack and queue built?

std::deque by default.

You can also use other sequential containers such as std::vector or std::list, by explicitly specifying them during creation:

#include <stack>
#include <queue>
#include <vector>
#include <list>

int main() {
    // Stack based on std::vector
    std::stack<int, std::vector<int>> vec_stack;

    // Queue based on std::list
    std::queue<double, std::list<double>> list_queue;

    return 0;
}

The default container (std::deque) is chosen because of its efficiency for insertions and deletions at both the beginning and the end, which is necessary for implementing stack (push/pop at the end) and queue (push at the end, pop at the beginning) logic.