UI Trends. Flat Design

http://www.tvidesigns.com/design/biggest-ui-design-trends-of-2013-so-far/

http://99designs.com/designer-blog/2012/06/20/7-user-interface-design-trends-you-need-to-know-about/

http://dribbble.com/shots/968985-HQ-Stylesheet/attachments/111425
http://dribbble.com/shots/1111316-Simple-Browser-Concept/attachments/140564

Skeuomorphism
Skeuomorphic user interface design was first popularized by Apple, and then adopted by many other companies. Basically, this design approach relies on imitating the look and functionality of traditional and familiar objects to make the interface more intuitive. For example, using wooden bookshelf with book covers to represent digital content is a prime example of skeuomorphism at work.