Monument Valley, an indie puzzle game based on optical illusions and impossible objects, generated nearly $14.4 million of revenue in two years after its launch; An ordinary dress prompted an Internet discussion around the world of whether it was black and blue or white and gold; Artists applied visual illusion to large 3D artworks which are so fascinating that a mass of spectators are willing to pay for taking a photo. Optical illusions can be seen everywhere in our lives, from interior design, installation, 3D art, product, to brand identity, book cover, and typeface design. They can always draw a wide public attention and bring economic benefits. This book has summarized 14 principles of visual illusion and 8 creation techniques, and included more than 60 amazing optical illusion artworks. Most important, it enables readers to create visual illusion flexibly and effectively either for personal interest or for commercial project.