Microsoft has announced that you'll soon be able to play your Xbox 360 games on Xbox One.
Phil Spencer announced the new feature during the Xbox media briefing, which functions a little differently to how you'd expect. Microsoft plans to release digital versions of every Xbox 360 game they can (pending the specific publisher's permission), which are all natively compatible with Xbox One features like Broadcasting and multitasking.
If you've ever bought one of these games on Xbox 360, you'll instantly be able to download the corresponding Xbox One digital version and play it. If you have a retail disc, insert it and you can then download the game from there. Cross-platform multiplayer will be supported too!
It's a massive step for Microsoft and a huge headline in general. The only issue we can see is that publishers have to okay it, meaning that we may well see omissions if there are HD re-releases out.
UPDATE: Microsoft have released an FAQ with more details about the service. 18 backwards-compatible games will be available as part of the next preview update, followed by 100 at launch. It also supports cloud saves, though many Xbox 360 games sadly didn't.