The material design evolved as a Universal Design language for interfaces. Google has unified their products design language to material design. Material design is a pretty strong visual language for interfaces. Meaningful interactions, Bold colors, natural shadows all these aspects are the basics of Material design.
We can see a lot of websites using the principle of material design for their interfaces. As it gains popularity there is a strong community has developed. Developing a website based on material design is not hard as you think these days. There are many front end frameworks are now available based on material design.
When we talk about website design, WordPress is the king of all. There is a good amount of material design WordPress themes are available in the market now. Even in CSS Author, We have adopted a bit of materialism. I have found some good Selling material design themes in theme forest. Which is a great evidence of its popularity.
See also : 300+ Best Responsive WordPress Themes
This post is a roundup of great free material design WordPress themes. You can see some great free WordPress themes here. All these are quality free to download WordPress themes.