Released when Aaliyah was just 15, Age Ain’t Nothing but a Number remains one of the best-loved albums of '90s R&B. Expertly produced from top to bottom by R. Kelly, it has aged better than Kelly’s works from the same period. While much of the era’s R&B now sounds dated, Aaliyah’s abilities are timeless. Her voice is as cool and ethereal as a princess’s, but she has the real-life presence of a teenager. In songs like “At Your Best You Are Love,” she translated the sensation of being young and lovelorn with an authenticity that older performers—even experts—couldn't grasp.