Smartphones have transcended their status as luxury possessions – they're practically considered a necessity. So it’s probably not surprising that mobile shopping is on the up – in the UK, it's set to rise by 77% in 2015. And thanks to Barclays Pingit, now you can even pay for stuff via Twitter.

Whether pinging your colleague a PDF or sending a mate an mp3, email attachments are the norm. And Google Wallet now allows UK users to attach cash to their emails, too. But in a financial landscape rife with privacy concerns, do people really want bank transfers to be as easy as sending an email?

While most people pay for goods online in their native currency, as mobile payment systems mature - boosted by Apple Pay - and new currencies flourish, soon digital wallets may have a new job: helping pick the best currency for each transaction.

Apple is hoping that Apple Pay, a tap-to-pay service integrated into the iPhone 6 and Apple Watch, will help it dominate the $79.2 billion-a-year digital payments market. But can Apple succeed where so many have failed before, and truly replace our wallets with our phones?