That service will offer the stock streaming experience, with rumors pointing to offline music playback support, customized playlists based on a user's listening history, and more.
YouTube Music Premium - $9.99 per month, ad-free, listen in background and downloads.
YouTube Music already has Google Assistant integration, but Lefsetz's demo makes it sound like it's been put on steroids.
In tandem with the YouTube Music launch, Google also revealed that YouTube Red - its paid subscription service that removed ads from across the whole of YouTube and offered original content too - will now become YouTube Premium.
The new YouTube Music will initially roll out in five territories - the U.S., Mexico, South Korea, Australia and New Zealand - with 13 European countries and Canada to follow at an unspecified later date.More news: The Nokia X6 Has Been Officially Announced
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YouTube Premium, including the streaming service and original shows will cost $11.99 for new members.
United Kingdom prices haven't been announced, although Google says the plan will be coming soon to new markets.
"The days of jumping back and forth between multiple music apps and YouTube are over", wrote Elias Roman, product manager for YouTube Music, in a blog post. If you like an artist or genre, YouTube Music will put their new singles and albums right on your homepage, so you don't find out about Daughtry's new single months after it came out like me. For those who are already subscribed to Google Play Music, they won't have to worry about anything. Soon, it will be its own service, complete with a new desktop player.
In reality though, it's likely to be the sheer breadth of music available on YouTube that will provide much of the appeal. "You'll still be able to access all of your purchased music, uploads and playlists in Google Play Music just like always".
YouTube Music will combine millions of "official" tracks with the vast catalogue of rarities and remixes uploaded by YouTube's users.