iOS 9 to be released September 16

iOS 9 – the latest version of Apple's smartphone operating system – will be released as a free upgrade for iPhone, iPad and iPod Touch users on September 16. First announced at WWDC, iOS 9 is an update focused on usability and performance, rather than features.

iOS 9's flagship feature is a major upgrade to Siri, Apple's virtual assistance. With iOS 9, Siri will respond to new verbal commands, have system-wide awareness, improved searching capabilities, and context-based suggestions.

Siri will be able to search through photos and videos based on dates, locations and album titles, in addition to being able to set reminders about what a user is currently doing on their phone. If a user is reading an email, they can simply tell Siri to "remind me about this when I get to my car", which will set a reminder linked to that exact exchange. In addition, Apple is giving developers the ability to expose their app's data to Siri, allowing users to search an app such as Airbnb without having to open it.

Apple describes the new Siri as a "proactive assistant". Siri will be able to suggests apps the user might want to use – based on the time of day – on the device's lock screen, provide caller ID for unknown numbers using emails as a source, and automatically add appointments to a user's calendar.

Other key features include a power saving mode, a brand new News app, and a heavily upgrade Notes app.

On the iPad front, iOS 9 adds in split-screen multitasking. The iPad Pro, iPad Air, iPad Air 2, iPad mini 2, iPad mini 3, and iPad mini 4 will all support Slide Over, a feature that lets users open a second app without closing the first. This second app can be pinned to the iPad's screen, and will stay open even if the user closes the first app and opens another.

iPad Pro, iPad Air 2, and iPad mini 4 users have access to a more powerful version of this called Split View, where two apps can be open and active at the same time.

iOS 9 can be installed on any device running iOS 8; unlike in previous upgrade cycles, no iOS 8 devices will be left behind. The update will approximately be a 1.3GB download.

The iPhone 4s and up, iPad 2 and up, fifth generation iPod Touch and up, and iPad mini and up are all compatible with iOS 9.