http://www.newsweek.com/ios-15-apple-update-support-devices-new-features-1631187

The new iOS 15 software update is now available to install on iPhone devices. Here is everything you need to know about the improved operating system and its various features.

iOS 15 is compatible with the iPhone 6s and every model that was released thereafter. This means that if you have a version that was produced between September 2015 and now, then your phone will be eligible for the update.