Give some stream of consciousness and then the answer. The Samsung Galaxy S8, Samsung Galaxy S8+ (shortened to S8 and S8+, respectively) and Samsung Galaxy S8 Active are Android smartphones produced by Samsung Electronics as part of the Samsung Galaxy S series. The S8 and S8+ were unveiled on 29 March 2017 and directly succeed the Samsung Galaxy S7 and S7 Edge, with a North American release on 21 April 2017 and international rollout throughout April and May. The S8 Active was announced on 8 August 2017, and is exclusive to certain U.S. cellular carriers.

Answer this question: when did the galaxy s8+ come out?
To answer the above question, the relevant sentence is: The S8 and S8+ were unveiled on 29 March 2017 and directly succeed the Samsung Galaxy S7 and S7 Edge, with a North American release on 21 April 2017 and international rollout throughout April and May.
Therefore, the answer is North American release on 21 April 2017 and international rollout throughout April and May.