Madonna is an American singer, songwriter, actress, and businesswoman. She achieved popularity by pushing the boundaries of lyrical content in mainstream popular music and imagery in her music videos, which became a fixture on MTV. Madonna is known for reinventing both her music and image, and for maintaining her autonomy within the recording industry. Music critics have acclaimed her musical productions, which have generated some controversy. Often referred to as the "Queen of Pop", she is cited as an influence by numerous other artists around the world.