Uber is designed to be an entirely cashless experience in most cities.
When a trip ends, the payment method selected for your trip is immediately charged. A receipt is emailed to you, and your account's trip history is updated with details about the route and fare.
A tip is not included in the fare and tipping is not required on Uber rides. However, you are welcome to do so in cash, through the app, on riders.uber.com, or from your emailed trip receipt, where available.