Microsoft Office 365
is a commercial software plus services offering a set of products from Microsoft Corporation, with the initial plan including a Professional subscription (for organizations of 25 and smaller) and an Enterprise subscription (for organizations with more individuals).  Office 365 was announced in the autumn of 2010, and was made available to the public on 28 June 2011.
Office 365 includes the Microsoft Office suite of desktop applications and hosted versions of Microsoft’s Server products (including Exchange Server, SharePoint Server, and Lync Server), delivered and accessed over the Internet, in effect, the next version of Business Productivity Online Services (BPOS).
On June 28, 2011, Steve Ballmer, chief executive officer, Microsoft announced
the availability of Office 365, Microsoft’s next generation productivity
service. Office 365 is the culmination of more than 20 years of experience
delivering world class productivity solutions to people and businesses of all
sizes. It brings together Office, SharePoint, Exchange, and Lync in an
always-up-to-date cloud service. Customers may try it and buy it at www.office365.com.