I have heard about linking a credit card to bitcoins. How would this be possible? For example there are now numerous bitcoin credit cards. How do they work exactly? Many seem to be fly-by-night companies.
There are two basic ways they work:
1) "Push" credit cards such as BitPay: With a "push" credit card, you push bitcoins to the credit card. When you do so, they are converted to local currency (typically dollars) and added to the balance available on your card. Payments draw from your dollar balance, not your bitcoins directly.
2) "Pull" credit cards such as Shift: With a "pull" credit card, bitcoins are is pulled from your wallet when you make a payment. Shift's credit card pulls bitcoins from your Coinbase wallet every time you make a payment, rejecting the payment attempt if you don't have sufficient bitcoins.