Samsung Galaxy S II

The Samsung Galaxy S II (also known as the Samsung Galaxy S2) is a touchscreen-enabled, slate-format Android-based smartphone 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 2.3.4 "Gingerbread", with updates to Android 4.1.2 "Jelly Bean".

Samsung unveiled the S II on 13 February 2011 at the Mobile World Congress (MWC) in Barcelona. It was one of the slimmest smartphones of the time, mostly 8.49 mm thick, except for two small bulges which take the maximum thickness of the phone to 9.91 mm. The Galaxy S II has a 1.2 GHz dual-core "Exynos" system on a chip (SoC) processor, 1 GB of RAM, a 10.8 cm (4.3 in) WVGASuper AMOLED Plus screen display and an 8-megapixel camera with flash and 1080p full high definition video recording.

It is one of the first devices to offer a Mobile High-definition Link (MHL), which allows up to 1080p uncompressed video output to an MHL enabled TV or to an MHL to HDMI adapter, while charging the device at the same time. USB On-The-Go is supported, allowing users to plug an external storage device, such as a USB flash drive or a portable hard disk drive. The user-replaceable battery gives up to ten hours of heavy usage, or two days of lighter usage. According to Samsung, the Galaxy S II is capable of providing 9 hours of talk time on 3G and 18.3 hours on 2G.

The Galaxy S II was popular and a huge success both critically and commercially, selling 3 million units within its first 55 days on the market. It was succeeded by the Galaxy S III in May 2012.

The S II currently has the largest (unofficial) number of known Android releases, shipping with Android 2.3.4 and being unofficially upgradable to Android 13.