Answer Description
iOS is Apple's operating system for their mobile devices (iPhone, iPad, iPod Touch). IOS can also refer to Cisco's Internetwork OS, but not typically from a user.
Wikipedia
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that presently powers many of the company's mobile devices, including the iPhone, iPad, and iPod Touch. It is the second most popular mobile operating system globally after Android.
Originally unveiled in 2007 for the iPhone, iOS has been extended to support other Apple devices such as the iPod Touch (September 2007) and …
IOS - Wikipedia, the free encyclopedia