What is Microsoft Office Online Server?

Microsoft has recently released a new product called "Office Online Server", which is the next version of previous "Office Web Apps Server 2013. The announcement says, that "Office Online Server (OOS), which allows organizations to deliver browser-based versions of Word, PowerPoint, Excel and OneNote, among other capabilities", so that you can now operate a copy of the web-based solutions that Microsoft is offering as part of Office 365, for instance.

For more information, see the announcement blog post.