The Samsung Galaxy S II is a touchscreen-enabled, slate-format Android smartphone designed, developed, and marketed by Samsung Electronics, as the second smartphone of the Samsung Galaxy S series. It has additional software features, expanded hardware, and a redesigned physique compared to its predecessor, the Samsung Galaxy S. The S II was launched with Android 2.3.4 "Gingerbread", with updates to Android 4.1.2 "Jelly Bean".

The Samsung Galaxy S is a touchscreen-enabled, slate-format Android smartphone designed, developed, and marketed by Samsung Electronics; it is the first smartphone of the Samsung Galaxy S series. It is the first device of the third Android smartphone series produced by Samsung. It was announced to the press in March 2010 and released for sale in June 2010. Due to shortage of Super AMOLED displays, Samsung released a successor to the device called S scLCD or SL and ceased production of the original I9000 model.