Concepts are well supported and have been for a while and they are so great. Those alone make C++20 worth it. But Coroutines also make it worth it, if you build

Concepts are well supported and have been for a while and they are so great. Those alone make C++20 worth it. But Coroutines also make it worth it, if you build software that can use them well. Designated initializers change how I write code (for the better - by a lot). And of course std::span.