The golden ratio—often symbolized as the Greek letter Phi (Φ)—is a mathematical constant approximately equal to 1. 618033987.| The Interaction Design Foundation
Complementary colors are the colors that sit opposite to each other on the color wheel. As the name suggests, these colors help each other stand out.| The Interaction Design Foundation
Grid systems are aids designers use to build designs, arrange information and make consistent user experiences.| The Interaction Design Foundation