Hard Edge

Hard-edge painting is known for its economy of form, fullness of color, impersonal execution, and smooth surface planes. The term "hard-edge abstraction" was devised by Californian art critic Jules Langsner, and was initially intended to title a 1959 exhibition that included four West Coast artists - Karl Benjamin, John McLaughlin, Frederick Hammersley andLorser Feitelson. Although, later, the style was often referred to as "California hard-edge," and these four artists became synonymous with the movement, Langsner eventually decided to title the show Four Abstract Classicists (1959), as he felt that the style marked a classical turn away from the romanticism of Abstract Expressionism.

Hard-edge painting can either be abstract with an illusion effect

Or hard edge could be a person...hard-edge can also relate a lot to pop art. Here are some examples. This hard uses bright colors and mostly straight lines