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(Pocket-lint) - The new mobile operating system from Microsoft is finally here with Windows Phone 8.1, announced at Build 2014. Top of the feature list was Windows Phone's new personal assistant Cortana. Joe Belfiore, corporate VP of Windows Phone described Cortana as "the first truly personal digital assistant."

Named after the character from Halo, Cortana uses the same voice actress to give her life. Cortana has her own live tile to feed information the user might like in a Google Now style, with Cortana looking like a fusion of Siri and Google Now.

Cortana can perform searches, control calendars, send messages, make calls and more, offering diverse and dynamic voice control.

Cortana has its own "Notebook" which shows everything it has learned about the user, meaning it can be edited. It also gets to know a user's friends and family which can be placed on an "inner circle". This is useful for "Quiet hours" which only let the inner circle through during that time.

When searching for restaurants, Cortana will incorporate Bing's Yelp data so the user can narrow down choices but asking for specifics like star ratings.

Cortana can also be used as a local search via typing. Search for an email from a certain person directly from the search bar, for example. Or set a reminder by typing: "remind me when I get home to cook dinner for my wife," and it will recognise when the user is home to remind them.

Cortana can be extended through third party apps allowing you to control them via voice alone. For example a user can say: "Cortana get James Philips on Skype" and it will open the app and call that person. For US users HuluPlus can be used to add shows to a user's playlist. Facebook is also integrated, allowing users to ask what's happening with a certain person to instantly be taken to their feed.

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Cortana will initially be launching with a beta tag in the US, but Microsoft confirmed that the service will be coming to the UK and other territories in the near future.

Writing by Luke Edwards. Originally published on 2 April 2014.