Android L's Material Design principles explained by Google's Roman Nurik (video)
Android L comes with a brand new Material Design that is a huge evolution in the looks of Android and a step toward a more modern-looking design with simple, clutter-free visuals.
To better understand the new design and how new apps should be redesigned to fit in those new realities, the Android Developers channel has posted an explanatory video by Google engineer Roman Nurik. Nurik is best known for his DashClock widget and Muzei live wallpaper app.
source: Android Developers
Things that are NOT allowed: