So you want to buy some food, some clothes, some Lego - or a movie.

So we go shopping. We go to a shop.

At a shop we can see all sorts of things. Different colours, different brands, different prices, different sizes, different movies. All kinds of differences, all sorts of choices. All in front of you so you can see what they look like - and whether they fit ...

And when you've decided, you go to the counter or the checkout, pay your money and go away with whatever you've bought. You know what you've paid and you know what you've got for your money - and you know who you've paid your money to.

And if you're not happy with the service you don't go back.