Paypal

And what might the rules look like?

Seven banks, including Wells Fargo and Capital One, are launching a competitor to services like Apple Pay and PayPal later this year.

Peer-to-peer apps have become a lifeline for small businesses. But many formerly under-the-table cash transactions now leave a digital trail. 

Digital payment methods may render notes and coins obsolete in the United Kingdom and turn it into a cashless economy.

The threshold used to be much higher.

It can feel safer to send money with a mobile peer-to-peer app. Usage is expected to keep growing after the economy recovers.

Easy-to-use services that let shoppers pay in installments are growing in popularity. They can make online shopping more affordable, but they can also get consumers into trouble.

The purchase of Honey Science Corp. for about $4 billion will provide customer behavior insights earlier in the shopping process.

A look at the big banks' answer to Venmo.

"We really need to step up as companies," CEO Dan Schulman says.