How It Works
Whether you're buying in a store or buying online, everything you do is geared around a transaction: the basic exchange of money for goods or services. In a real-world store, you simply take your new jeans to the checkout, hand over some cash, and leave the store with your purchase in a bag—that's a transaction. It works in a similar way if you're buying online, but there's one important difference: you never actually get to handle (or even see) the goods until they arrive at your home sometime later.
If this makes buying online slightly problematic for the purchaser, it also introduces two extra problems for the retailer (or e-tailer, as online retailers are sometimes known). Apart from having some means of processing transactions online, it means they also need a way of checking that the goods you've ordered are actually in stock, and a means of dispatching and delivering the goods to your address.