Samsung Galaxy S
The Samsung Galaxy S was the first phone in the Samsung Galaxy S series and was the third android phone series that was started by Samsung .The phone was announced in press on March 2010 and was available in market in June 2010
Majority of the phones that Samsung launched were of the same design including the Samsung Star having almost the same design of the Samsung Galaxy S except that Galaxy S had no hard buttons as compared to Star and was functionally more capable
Samsung Galaxy SII or Samsung Galaxy S2
Samsung Galaxy S2 or SII was a successor of the Galaxy S series with re-modification of the design completely making it much more appealing. With this phone the Samsung Smartphone era had begun.
Samsung unveiled the phone in February 2011 and this phone was one of the slimmest phone of times. With sexy design and other features, the phone is still in continuation. In January 2013 an update to Android 4.1 JellyBean was made available and the recent news is that Android 4.2.2 will also be made available.
Samsung Galaxy SIII or Samsung Galaxy S3
Samsung Galaxy S3 was a successor of the Galaxy S2 with modified body and better performance . Samsung Galaxy S3 was that successful as compare to S2 but it had some amazing features .It was unveiled on May 2012. It was launched with a 4.8 inch screen. The device was launch at the end of May and the Starting week of June Worldwide.
Samsung Galaxy SIV or Samsung Galaxy S4
The most amazing phone till date was unveiled on March 14 ,2013 and was subjected to be in markets the following month. S4 was so amazing that the product went out of stock the first day itself when it was in market. The phone is specially famous for its features and its 5 inch screen.
Samsung Galaxy SV or Samsung Galaxy S5 (TBA)
Looking at the previous trend of how Samsung has launched its S series phone it is possible it might be unveiled In April 2014.
Samsung Galaxy SVI or Samsung Galaxy S6 (TBA)
Even though this is not official it is possible that its release date would be somewhere near around March 2015 as we expect . So keep waiting for the Official news.