It could be inventing a new kind of burger (Impossible Foods), a new way of selling eyeglasses (Warby Parker), a fashion concept (Stitch Fix, Rent the Runway), a virtual-reality headset (Oculus), a fitness tracker (Fitbit), an affordable smartphone (Xiaomi), a scooter- and bike-rental service (Lime), a genetics-testing service (23andMe), medical robots (Auris Health), a mental wellness service (Lyra Health), a payments service for merchants (Stripe, Square), or a consumer bank (Revolut, Monzo).