The iPhone 6S and iPhone 6S Plus (stylized and marketed as iPhone 6s and iPhone 6s Plus) are smartphones that were designed, developed, and marketed by Apple Inc. It is the ninth generation of the iPhone.

They were announced on September 9, 2015, at the Bill Graham Civic Auditorium in San Francisco by Apple CEO Tim Cook, with pre-orders beginning September 12 and official release on September 25, 2015.

Excerpt source – Wikipedia