iOS stands for a mobile operating system used by Apple company. iOS also used in iPad(Tablet model). The first iOS came in use at the 2007 year and it was iOS-1. It was used in iPhone 1st Gen.
The second version was upgraded into 3G and launched in the year 2010. It was used in iPhone and iPod touch.
The third version came in focus at 2014 and it was named iOS 3-GS.
Next version was 7.1.2 and launched in the same year 2014 June. It was named iOS or iPhone 4.
In the year 2016 upgraded version of iOS 4 launched by the name of iOS-4 S and its version was 9.3.5
Version 10.3.3 was named iOS 5 and 5C, launched in the year 2017.
Right now the latest version is 12.1 Beta 4 and it is launched in October 2018. This is the latest version of iOS all the iPhones.
Apple doesn’t declare any new or upcoming version after iOS Beta 4. So we need to wait and watch.