In its 2.0 update Sony explains how SharePlay is used correctly. SharePlay is a feature on where you can remotely share your game to a friend even if he doesn’t have the copy of the game. President of Sony Worldwide Studio Shuhei Yoshida has explained how it works on this website via Weekly Famitsu and was translated via Kotaku.

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Image source: Extremetech.com

Yoshida said, “How it works is, for example, say, a friend has a game that I don’t. I ask them to let me play it, and if they send me an invitation, I can access their PS4 and play while watching the video that is streamed. You could call it a mini PlayStation Now. There is no need for developers to do anything for their games to be compatible with SharePlay.”

SharePlay is basically gameplay streaming between 2 PS4's. If your friend wants to borrow your game for a while it means that you won't be able to use your PS4 to play any game while it's in use by your friend. It is like allowing a co-pilot to take control of the whole system, so make sure that when you lend your game, it's someone you really trust.

Right now, SharePlay is only limited to the PS4 library of games and won't work with its predecessor. It will be included in the upcoming 2.0 system update for the PS4 that is scheduled to be released later this year.