Released in 2003, "Ayer" stands as a defining track in the early career of Wisin And Yandel, the Puerto Rican duo that helped pioneer the modern reggaeton sound. The song exemplifies the genre's signature blend of dembow rhythms and Spanish-language lyrics, establishing a template for the Latin urban explosion of the mid-2000s. While often associated with their later collaborative project Los Extraterrestres, this recording showcases the raw energy and melodic sensibilities that would characterize their subsequent discography. The track remains a staple in the catalog of influential reggaeton recordings, reflecting the cultural shift toward Spanish-language pop dominance in the United States and beyond during that era.