Appropriation art is a postmodern practice where artists use existing images, forms, and ideas to create new works, reflecting the notion that originality is an illusion. This movement has roots in early 20th-century art and has evolved through various forms such as collage and pastiche, highlighting the complexities of authorship and cultural meaning. Influential artists like Andy Warhol and Sherrie Levine exemplify this trend by challenging traditional notions of originality and expanding the boundaries of artistic expression.