Office UI Fabric, Microsoft’s bootstrap?
Microsoft has released a new framework for developing an awesome front-end called Office UI Fabric. So the big question is why did Microsoft created this framework? We already have a ton of different frameworks for front-end development like Bootstrap, Semantic UI, 960 Grid System and many more.
The short answer is that we did not have a framework for creating Office or SharePoint add-ins that integrates with the looks of Office applications.