It has a network of 3700-plus bicycles scattered at 440-odd stations around the region. Kiosks issue passes (one day or three days) on the spot. Insert a credit card, get your ride code, then unlock a bike. The first 30 minutes are free; after that, rates rise fast if you don't dock the bike.
There's also an option for a 'single trip' ($2), ie a one-off ride of under 30 minutes. Note helmets and locks are not provided