History of Apple Inc.
The first version of the iPhone became publicly available on June 29, 2007 in selected countries/markets. It was another 12 months before the iPhone 3G became available on July 11, 2008. Apple announced the iPhone 3GS on June 8, 2009, along with plans to release it later in June, July, and August, starting with the U.S., Canada and major European countries on June 19. This 12-month iteration cycle has continued with the iPhone 4 model arriving in similar fashion in 2010, a Verizon model was released in February 2011, and a Sprint model in October 2011, shortly after Jobs' death.
IPhone OS 1
iPhone OS 1 is the first major release of iOS, Apple's mobile operating system. iPhone OS 1.1.5 is the latest and the last version of Apple's iPhone OS 1. This version of iOS was the first iteration of the touch-centric mobile operating system. No official name was given on its initial release; Apple marketing literature simply stated that the iPhone runs a version of Apple's desktop operating system, macOS, then known as Mac OS X. On March 6, 2008, with the release of the iPhone software development kit (iPhone SDK), Apple named it "iPhone OS" (they later went on to rename it "iOS" on June 7, 2010). It was succeeded by iPhone OS 2 on July 11, 2008.