See: Mobile Marketing. See: Mobile Advertising. See: Mobile Banking. (Yes, see this term again and enter The Matrix with Wick). Then see: Mobile Commerce.
So...if you have a Bank of America, Wells Fargo, or other normal banking app on your phone, and you take a picture of the paper check that Grandmama wrote to you for your birthday (that 5 bucks will go far), and you take that pic from the camera element on the banking app so that the check can be immediately deposited...that's mobile banking.
Congrats. You're in the modern age. If you have an extra two bucks, you can afford to ACH a latte.