Fabric embodies the Microsoft Design Language. You get to use the same design language used in Microsoft products, so your experiences feel tightly integrated into Office.
Fabric is just like other popular frameworks so it's easy to use. CSS classes, HTML, and JavaScript samples - everything you need to get going building great looking experiences.
Fabric is built from the ground up for Office so there is no excessive overriding of pre-existing frameworks.
Fabric integrates with other frameworks like Bootstrap. Uniquely namespaced classes prevent conflicts.
Fabric is built with LESS for powerful customization.
Full language support (including right-to-left behavior) helps take the guesswork out of localization.
Full access to the source code and samples. You can tailor Fabric to your own specific needs.