Cortana

Cortana is one of the signature features of Windows 10, combining local and web search with the ability to understand spoken commands and enough smarts to convert those commands into tasks, appointments, or instructions. Essentially, Cortana acts as a personal assistant, complete with an occasionally sassy personality (with the name and voice taken from the Halo franchise on Xbox).

Cortana is not enabled by default on Windows 10. The first time you click in the box to the right of Start, Cortana gives you the option to enable it or leave the feature disabled. If you don’t want users in your organization to interact with Cortana, you can disable the feature using Group Policy. Cortana setting, which is accessible under Computer Configuration > Administrative Templates > Windows Components > Search.

If you don’t enable Cortana, the box to the right of Start performs simple searches of the local file system, settings, and the web, minus any personality and also without any connection to your personal data.

Although Cortana has been part of Windows Phone for nearly a year, she appeared for the first time in the Windows 10 Preview in late January 2015. Because much of Cortana’s magical powers derive from web-based services, she’s getting smarter with age. What you see in current releases is only a fraction of what you’ll see after another year (or two or three) of continuous improvements.
The best way to understand Cortana is to type something into the box just to the right of the Start button, or click the microphone icon and say it instead.

After you and your users get past the novelty of it all, take a look at Cortana’s notebook (available from the icon just below Home in the navigation bar on Cortana’s left edge). That’s where you can fine-tune the information—news, upcoming appointments, weather, reminders, and so on—that pops up instantly when you click in the Ask Me Anything box. (That summary is replaced with search results as soon as you start typing.)

The list of Notebook categories isn’t complete, and within each category the options can expand as Cortana becomes more capable. Scrolling down reveals more categories, including Weather, Sports, and Reservations, where you can allow Cortana to scan your email in search of restaurant reservations, movie times, and other likely events.

Source of Information : Microsoft Introducing Windows 10 For IT Professionals