Star images are readily recognized signs that are used across various media. Celebrities allow their images to be used for advertising purposes. Several theories discuss how star images are constructed and used. Richard Dyer's star theory proposes that celebrities are produced by institutions for financial gain and targeted at specific audiences. Andrew Godwin and Sven Carlsson also theorize that an artist's unique star image plays an important role in music video production and develops over time. Lady Gaga's early work showed a simpler image than her later more revealing and outrageous style, as her star image evolved along with her music and message.