Microsoft unveils Cortana, a smartphone digital assistant that's a rival to Apple's Siri

Like Siri and Google Now, Cortana will mine users' personal data (with their permission) to offer reminders and try to pre-empt their needs

Microsoft CEO Satya Nadella introduces Cortana, which appears as an animated circle. (Getty)

Microsoft has finally unveiled its own digital assistant Cortana, a rival to Apple’s Siri that’s named after an artificial intelligence character from the videogame series Halo.

Cortana will replace the search function in the latest version of Microsoft’s mobile operating system Windows Phone 8.1, and can handle natural voice commands for tasks such as setting calendar events or reminders.

Google and Apple both offer similar features on their own mobile devices through Android’s Google Now and Siri on the iPhone and iPad, with users able to ask specific questions such as "How tall is the Eiffel Tower?" without having to type out a search.

All of these programs also analyse users’ browsing history, contacts and calendars in order to anticipate their needs – although Microsoft stresses that Cortana will ask for permission before looking through users’ data.

Microsoft showed off a number of features unique to Cortana including the option to take “people reminders”, notes for individuals which offer reminders – such as "ask about sister’s new puppy" – next time the user talks to them.

Cortana can also connect to third-party apps to offer users more information. Asking about nearby restaurants will bring up user reviews from sites such as Yelp, while enquiring after a specific friend might direct someone to their recent activity on Facebook.

Cortana as she appears in the videogame series Halo (left) and on Windows Phone (right).

Microsoft will be hoping features like this will lure people towards their mobile operating system but so far Cortana does not appear that different to Siri or Google Now.

The unveiling of the software at Microsoft’s developer conference Build 2014 was also mired by a few technical glitches, including Cortana refusing to make a phone call.

Joe Belfiore, Microsoft’s head of Windows Phone, said that at times like that users can simply type in their request by hand.

Although Cortana is named after a specific fictional character (and is even voiced by the same actor - Jenn Selby) the software appears only as an animated circle; albeit, one that spins and glows when processing requests to inject a bit of personality into the software.

It may be a long way off the convincingly human artificial intelligence that appeared in Spike Jonze’s Her, but it’s certainly another step towards a future where our smartphones’ really do act as digital personal assistants.