Playlists in the iPhone/iPad app

What is the function of playlists in the iPhone app? How do I get content into it? Is this content kept locally in the device?

Swipe a lesson and it gives you an option to add to playlist.

And is the lesson saved locally on your device?

Yes, lessons added to playlists are kept locally on that device. Playlists allow you to play a list of lessons all at once, repeat and shuffle them. Also, any lessons added to playlists are downloaded when added to the playlist so that you don’t have to open each lesson ahead of time if you want to use the lessons offline. I always listen to my lessons using playlists since it is convenient to download them this way and all my listening time is then tracked. Unfortunately, lists are not synced with the site or other devices although it is on our wishlist.