Spotify on Wednesday expanded the free tier of its service to all devices, including smartphones and tablets.
In the past, free Spotify users could only access Spotify Radio on mobile devices and tablets, but like other radio services, this prevented them from listening to a specific artist or music in their own playlists. The new offering expands on-demand listening to free users on tablets, and allows smartphone users to listen to their own playlists or music from a specific artist in shuffle mode.
See also: Spotify Expands Free Streaming to All Devices
Spotify created the following chart, which shows the access options that users have:

When it comes to specifics on how everything works, it becomes a bit more complicated. Fortunately, Mashable spoke with Charlie Hellman, Spotify's vice president of product, who broke down the company's new mobile offering.
You can listen to any song you want, and in any order, if you use Spotify on a tablet. On iOS, this means the iPad or iPad mini. On Android, Spotify is setting 7-inches in diagonal as the screen minimum for tablets. The app will determine which version of the experience you see in Android.
On the tablet, the play-on-demand feature works the same as it does on desktop. You will have ads every five to six songs, and you can't save playlists for offline listening. Spotify decided to treat the tablet as a desktop after observing how people use the product.
In a post-PC world, the tablet is increasingly becoming the main home computer for many consumers, including Spotify users; for that reason, the company chose to make the experience on-par with what you'd get on the desktop.
On smartphones, only Spotify Premium users have the option to listen to specific songs on-demand.
Although Spotify doesn't offer free on-demand listening via mobile, it has substantially expanded the types of music you can listen to, and how you can listen to them.
You can now listen to music from any artist in "shuffle" mode; this means you can search for an artist, then instantly listen to a station that only features that particular artist. It's a big switch from typical online radio services, such as Pandora and iTunes Radio, which may let you create a station around an artist, but wind up having other artists in the mix, too.
What's more, you can listen to your own Spotify playlists in shuffle mode. Be aware, however, that there are a few rules about how they work.
Your playlists will need to meet several parameters to work in free shuffle mode. (Don't worry, Spotify will automatically fill out your playlist if it doesn't meet these requirements.)
They include:
A playlist must have at least 20 songs
A playlist must consist of at least three albums
Even if you list the same track 20 times in a row, it still only counts as one
Spotify said the vast majority of playlists have more than 20 songs, and include many different artists. Although this means you can't listen exclusively to a shuffled mix of Daft Punk's Random Access Memories, you can listen to Rolling Stone's playlist for its top 100 tracks of 2013.
Plus, as long as you add a few songs from other albums to your Random Access Memories playlist, you'll be guaranteed to hear the whole album during your listening session.
The biggest change is that you can choose to only listen to a specific artist — something the other services don't offer. What's more, you can listen to playlists you create.
Songza is a playlist-oriented Internet radio product, but its licensing rules mean that users can't listen to playlists they create themselves.
This is also true for other streaming services that offer access to curated playlists. Usually, it's fine, especially when users are passively listening to tunes. Where it becomes problematic is if you've collected a bunch of tracks for an event, such as a holiday party. What's the point of having the ultimate holiday playlist if you can't even play it back on your own device?
Yes. Free users can create their own playlists or add songs to existing playlists in the app; this means if you want to add a track from Spotify Discover to an existing playlist, you can do so without having to worry. You can also create new playlists with music or artists you come across.
Just as they do on the desktop and within Spotify Radio now. Interruptions and ads will come every five to six songs.
This will totally depend on how you listen to music. If you mostly listen to playlists while on your phone, and avoid selecting albums and tracks, you may not feel the need to pay for Spotify Premium. What's more, if you use an iPad or Android tablet for most of your listening, you no longer need to pay to play any song you want.
Still, Spotify Premium continues to have advantages. On the smartphone side, the biggest advantage is that you don't have to deal with ads, and you can save music for offline listening; this is really useful when on an airplane or the subway. Spotify Premium users can also stream audio in higher quality, so if you're an audiophile (at least in the context of streaming music), you get higher fidelity sound.
Spotify told Mashable that getting rid of ads and offline playback are actually the two biggest reasons users upgrade to Spotify Premium. The goal of the new Spotify freemium offering is to encourage users to listen to as much music as possible.
"We've found that the more stuff we give users, the more users are willing to pay us," Hellman said. It's a good point. I know I have personally found that the value in subscription music services really shows itself the more I use it. Having more mobile listeners gives Spotify a chance to convert more of those listeners into Premium subscribers.

Make sure you are running the latest version of Spotify for iOS or Android, and the option is available now. For free users, browsing artists or accessing your playlists will show an option to "Shuffle Play."
On Android tablets and the iPad, you now have the ability to listen to any track you want at will.
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Images: Spotify