An article on MONEY, the financial section of Time’s web portal, explains that big companies like Dell, PayPal, Expedia, and Microsoft partner with bitcoin operators like Coinbase or BitPay in order to accept customer payments in bitcoins.

2014 has seen a remarkable rise in bitcoin’s popularity among large retailers. Major brands such as Microsoft, Amazon, and eBay announced partnerships with digital currency operators, starting the process of integrating bitcoin in their systems.
According to MONEY, merchants convert their bitcoins immediately into fiat because they do not trust the digital currency. Patrick Byrne confirmed in May that Overstock keeps only 10% of its bitcoin income in the cryptocurrency, exchanging the rest into U.S. dollars.
MONEY’s expert, Jacob Davidson, explains the lack of trust in bitcoin among major businesses is the result of its volatility. Nevertheless, he notes that as more companies begin to accept the digital currency – even through mediators – bitcoin will become ever more useful.

The article point in particular to the crucial role of payment operators in the spread of bitcoin among large retailers: “Cryptocurrency fans should be naming their first born children after Coinbase and BitPay executives since there would probably still be no major businesses accepting bitcoin at all without these companies offering full conversion services.”