C++: What are C++ ranges (C++20)?

1#include <ranges>
2#include <vector>
3
4std::vector<int> v = {1, 2, 3, 4, 5, 6};
5
6// Lazy pipeline
7auto result = v
8    | std::views::filter([](int n) { return n % 2 == 0; })
9    | std::views::transform([](int n) { return n * n; });
10
11for (int n : result) {
12    std::cout << n << " "; // 4 16 36
13}