Material Design is the new, much-hyped, design style. It replaced flat design as the new must use design. Material Design was introduced by Google in 2014 and it expanded the card motifs of Google Now. The following is an image of a Google Now card:
Google Now card.
The whole idea behind Material Design is to build upon the grid based system, the responsiveness of animations and transitions, while adding depth to the design. Matias Duarte, the lead designer behind Material Design, put it this way:
"Unlike real paper, our digital material can expand and reform intelligently. Material has physical surfaces and edges. Seams and shadows provide meaning about what you can touch."
Material Design is a set of very precise and complete specifications that can be found here: https://material.google.com/.
Anyone with solid knowledge of CSS3 and HTML5...