Mobile payments: The cheque is in the tweet HANDLING small transfers between individuals is not an especially big or lucrative part of the financial system, but it is a faddish one. On November 17th Snapchat, a popular app that lets users send each other photos that disappear after a few seconds, introduced a new service called Snapcash that allows them to transfer money (with luck, no vanishing is involved). The news comes hot on the heels of the announcement from Groupe BPCE, a French bank, that its customers will soon be able to send each other money via Twitter, a microblogging service. Facebook, a social network, has similar plans; Apple, which recently launched a payment service, may also join the fray. Person-to-person (P2P, in techno-speak) payments are growing fast. Last year Forrester, a market-research firm, predicted that mobile P2P payments in America would amount to only $4 billion a year by 2017. Now it expects the market to reach $5 billion this year and to grow by 26% a year, to reach $17 billion by the end of 2019. Two-thirds will be domestic transfers, the rest international remittances. Venmo, a P2P startup now owned by PayPal, an online-payments firm, says that it transferred $700m in the third quarter of the year, 50% more than in the second. Using mobile phones to send cash is nothing new. The granddaddy of such services is Kenya's M-PESA. Launched in 2007, it is now used by more than 17m Kenyans, equivalent to more than two-thirds of the adult population. PayPal has had a mobile-payments app for some time and is the market leader in America. Big banks have also entered the P2P business, with services such as Popmoney in America and Paym in Britain. What is changing is that such services are getting ever easier and faster to use, with some now offering instantaneous payments. In the case of Square Cash users open an account with their debit card and can send money to any e-mail address or mobile phone number (recipients need to open an account, too). Snapcash allows users to flick money to their friends by dragging images of notes around the screen of their smartphone. Venmo is an example of another trend: it makes mobile payments "social," in that it allows groups to split bills easily at restaurants, say, and share information about transactions. The app lets users send messages along with payments ("To Misha and Nina, for such a fun evening") and make them - although not the sum involved - visible to friends. Although all this may make older users yawn or cringe, younger ones, the majority of Venmo's customers, seem to like it. The ease of use and the social element raise concerns about security. Snapchat does not have the best record in this respect: in October tens of thousands of supposedly vanished photos sent via the app appeared online. But providers point out that their services run on regulated payment platforms, where all the sensitive data are kept. Snapchat, for instance, uses Square, a payments firm, which also operates Square Cash. All services impose a limit on transfers: in the case of Snapcash it is $250 a week (although that can be raised to $2,500). Another burning question is how all these services will make money. Some charge fees. Popmoney, for instance, sets you back $0.95 per transaction. Others may introduce premium services, try to monetise the data they gather on payments or sell advertising. But consumers, at least for domestic transfers, will come to expect real-time, free P2P services, predicts Denée Carrington of Forrester. "Nearly all offerings are loss leaders," she says. All this is a threat to banks, reckons Ms Carrington: they want to remain the main conduit for consumer spending and money transfers, which is why most now have their own P2P payment offerings. But what if consumers, in particular the younger ones, prefer the services of newcomers? In some circles in America "Venmo" is already used as a verb, as in "Can you Venmo me some money?"