It started as Rap Genius, crowd-sourcing comments on song lyrics, and evolved into Genius, a large-scale publisher serving video, audio, and “encyclopedia of music” content to a devoted community of fans: 1.6 million followers on YouTube alone. I visited their spacious Gowanus headquarters — the ground floor converts easily into a club — to hear from Ji Krinsky, VP of brand partnerships, how Genius is leveraging its organic relationships with musicians and celebrities to help brands (especially in fashion and entertainment) offer experiences to a unique, valuable, and well-defined audience — all 85 million of them.