Should floors be darker or lighter than walls?

While there is no rule that states that you should have dark floors, a darker floor makes the space look more attractive and grounded. The combination of lighter walls with darker flooring creates an illusion of space which makes this a preferred style among homeowners.

Image Source: The Flooring Girl

However,  you can use the opposite combination of lighter flooring with opposite walls when you have a low ceiling in order to create an illusion of height.