is that you aren't spending your own money - you are effectively borrowing it from the Card provider on the understanding that you'll pay it back in instalments - if not all in one go. When you use the card to buy something you're topping up your loan, but it's the card provider who is paying the retailer - that's why the whole system works. No retailer would sell you goods on the basis that you would pay for them later, but that's what happens when a credit card sale is made - the retailer trusts the card provider to pay, and the card provider trusts you to repay the loan.
If you buy goods using a credit card (not a debit card) or the retailer has arranged credit with a finance company on your behalf, section 75 of the Consumer Credit Act of 1974 provides protection, as long as the price of the item was over £100. This is the case even if you have only paid a proportion of the cost using a credit card - a deposit for instance.
When you use your credit card to make a purchase of goods or services over £100 the card provider becomes equally liable with the retailer for breaches of contract, or misrepresentation. If a retailer you had purchased from ceased to trade for instance, you would look to the card provider for compensation under section 75 of the Consumer Credit act of 1974, although you would be expected to contact the trader in an attempt to obtain recompense first. In such circumstances you should write to the card provider to say that you wish the matter to be noted as being 'in dispute' and tell them that you would look to them for compensation if you don't obtain satisfaction from the retailer.
Does that help?