This is the official site of Material Design, where you get to learn the criterion of Material Design. Here you’ll also find useful tools, such as online color match and coordination aid for development, though some of the tools require application.

It’s worth mentioning that in the Icons section, there are over 900 icons of the unique MD style, which come in various formats and sizes. You’re free to use them as you please, except, of course, to sell them.