Outlook.com is a web-based suite of webmail, contacts, tasks, and calendaring services from Microsoft. One of the world's first webmail services, it was founded in 1996 as Hotmail (stylized as HoTMaiL) by Sabeer Bhatia and Jack Smith in Mountain View, California, and headquartered in Sunnyvale. Hotmail was acquired by Microsoft in 1997 for an estimated $400 million and launched as MSN Hotmail, later rebranded to Windows Live Hotmail as part of the Windows Live suite of products. Microsoft released the final version of Hotmail in October 2011, available in 36 languages. It was replaced by Outlook.com in 2013. Outlook.com follows Microsoft's Metro design language, closely mimicking the interface of Microsoft Outlook. It also features unlimited storage, a calendar, contacts management, Ajax, and close integration with OneDrive, Office Online and Skype. In May 2015, it was announced that a preview of the new Outlook.com will move it to the Office 365 infrastructure. Microsoft concluded its preview stage in February 2016, when it began to roll out the new version to users' accounts, beginning with North America. As of 2015, Outlook.com had 400 million active users.