Samsung will help the Android Marshmallow with improving the quality of the upcoming firmware update. The company is running a beta of the newest software. The company chose the S6 and the S6 edge to be the phones taking part in this experiment.
For now, the beta is available in the South Korea only, but it will be expanded to the other markets.
The goal is to catch all the bugs and to improve the quality of the Marshmallow. It can be downloaded in the Play Store (in Korea, at the moment).