Typically, wild or common rats, known as brown rats or Norway rats, have brownish-gray fur. This coloration allows them to blend into various urban and natural environments where they are commonly found. However, the specific coloration of brown rats can vary somewhat, with shades ranging from light brown to dark gray. Their fur is generally uniform in color, with the belly being slightly lighter than the back. The tail of a brown rat typically matches the color of its body, appearing brownish-gray as well. It's important to note that domesticated pet rats come in a wide range of colors and patterns due to selective breeding, while wild rats generally exhibit the typical brownish-gray coloration.