Isotope Product Rating
Websites are different and so are their designs. To make sure that the extension fits any, there are two different rating star designs provided by default: vector and image. They can be adjusted in the product rating configuration.
The vector stars are generated in the frontend using the special font. Mechanism is pretty the same like of the popular FontAwesome library or any other font-based icon sets. This gives some nice styling possibilities as your are able to set the stars size and their color without a need to create any images.
If you prefer the image stars however, there is also a solution for that! The other style included in the product is based on real PNG images. There is a default image set included in the module, however you can set your own images for full, half and empty stars in the rating configuration.