Many people sell things via the Web. Statistics — always of varying quality — concerning how many people are buying things, selling things, and how much money is being transacted, abound. There are predictions of the future value of on-line sales stretching into trillions of dollars. Some predictions even claim that the majority of items bought and sold in the world will eventually be bought and sold over the Internet.

Even with a healthy scepticism of statistics and predictions, it is still clear that there are many Internet sales currently taking place, and that this number seems likely to only increase.

This section explores the following questions:

Selling on the Internet has largely the same advantages and disadvantages as advertising on the Internet.

Wholesalers buy a particular product in bulk and sell it on to retailers, who deal directly with the customer. Internet sales break down this relationship. This can have both positive and negative effects on the industry concerned. One positive consequence of introducing Internet sales is that it cuts out the middlemen (i.e. the wholesalers and retailers), and therefore the product price can be reduced. However, eradicating wholesalers can be a risk to the supplier. Since wholesalers buy the product in bulk, they pay for the space to store your product, and also take the risk of buying the product without knowing its shelf-life. Retailers deliver the product to the customer and handle the majority of customer complaints. Selling directly to the customers removes these middlemen, so successful Internet sales require the implementation of the following:

When selling something over the Internet, money has to be transferred between people. Money transfer is a potential target for misuse and is therefore a possible security problem. However, this problem has been studied for many years and there are now a number of technologies, largely encryption-based, that exist to secure communication channels. Under this approach, information about the purchase, including the user's credit card details, is encrypted in such a way that the seller is the only one who can decrypt it. Hence, the transaction is secure.

Examples of these technologies include cyber-cash, digital signatures and PGP encoding of the transaction.

Of course, the provider (the person building and supporting the site) must provide the security features. These may be transparent to the user (i.e. the user is not required to do anything special) but they must exist.

A major concern to customers is that their details are adequately protected. Customers should be provided with assurances that their transactions are indeed secure, and there should be explanations of how this security is ensured.

Security complicates matters, but adequate precautions can be taken. Currently a customer is more likely to be defrauded by a waiter in a restaurant via a credit card transaction than by someone gaining access to a secure communication channel used for e-commerce.

For a more thorough discussion of security see Unit 13.

High level usability considerations such as consistency, adequate feedback, good use of screen geography, colour and sound, navigability, on-line help, and so on, are as important for a website as it is for other interactive systems. Indeed, some would argue that they are even more important.

Sites should be easily understood by a first-time user. It is important to realise that if a first-time user does not find the site usable, it is unlikely that they will return.

A site needs to guide the visitor through the transformations in the DAGMAR model is an easy and confident manner. This means that a visitor should be able to browse a collection of products on offer, browse the products' details, receive a demonstration of any particular product, purchase a product, and feel confident that the transaction has been performed correctly and safely. Usability is a key consideration at every step. For example, if it is not clear when the purchase has been accepted, not only is it frustrating for the user, it might result in multiple purchases being inadvertently made — or, indeed, no further purchases at all.

One important user task is the ability to browse a product list, perhaps to confirm product details or access further product information. Whatever the reason, the implementation of this task should be well considered, especially how the product list can best be displayed, ordered, and searched. Simply listing the products in numerical order will not support even a simple product search: users likely do not know the product's position in the list, and it is incorrect to assume that users know exactly which product they wish to buy when the first visit the site.

While usability is important to an advertising site, it is even more essential at a point of sale — this is the only chance customers have to confirm that they want a product before they buy it.

Providing a mechanism to enquire about the products on offer is a minimum user requirement. This can be achieved by, for example, providing the e-mail details of a virtual shop attendant. This is, essentially, one type of on-line help system.

Repeat visitors / customers should also be considered. It is possible to ignore them, but if customers are expected to repeatedly purchase products it becomes good customer relations (and good usability) to provide website functionality targeted towards them. This could be done by keeping an individual record of a customer's purchases, including how often they have visited the site. If a high percentage of a customer's recent visits have resulted in the purchase of the same or similar goods, it might be appropriate to offer them these goods on their next visit, or to suggest similar products. A record of customer details, such as address and payment details, could be stored, which stops customers from having to repeatedly supply these details for every purchase.

Remember that Internet commerce sites are expected to be highly interactive, and should provide high levels of support for the customer.

The details of how a user browses, inspects, selects, and purchases items differs from site to site. However, a common metaphor has been developed: that of the 'virtual shopping trolley', or 'virtual shopping cart'.

The metaphor can be thought of as going to a supermarket: items are taken from various shelves and placed in a shopping trolley. The customer carries the items with them as they move through the store, and are free to add more things to the cart or even to return items to the shelves. Once the customer has selected all the items that they want, the trolley is taken to a cash register and the goods are paid for.

Using this metaphor for on-line shopping is usually a good thing, as lots of people are already familiar with it from their own lives. A virtual shopping trolley operates in much the same way as a real trolley: items can be selected from those available on the site and placed in a virtual trolley. Once in the trolley they can be examined further or returned to the store. Finally, once the customer has finished selecting all of their goods, all the goods in the trolley are paid for and shipped to the customer.

While this is the basic shopping trolley metaphor, further functionality can be added to it. For instance, a website can, for the customers' convenience, keep a running total of the cost of the items in the trolley.

Once the purchase has been completed, the products must be delivered. Sometimes this is trivial: if the 'product' is a hotel reservation, confirmation can be sent by email and nothing physical need be delivered. Software can also be delivered over the Internet (through email, or FTP, for instance), although if the software comes with paper-based support materials, such as a manual, then physical delivery is still an issue. Most items need to be physically delivered. The problem of physical delivery is also faced by telephone and mail orders, and so is nothing new.

It is important to remember that since the Internet gives access to a global market, a company's existing delivery channels may not be adequate for their website's potential customer base. One common form of delivery is Express Mail, which allows books, music, documents, and other small items to reach anywhere in the world for a reasonable price. However, alternative possibilities will be required for some items: for instance, a store may not be able to deliver fresh flowers through standard Express Mail, but it may be possible to fulfil orders using a store close to the customer.

Useful functionality for an e-commerce site is to allow customers to check on the progress of their delivery, such as by finding where their order is in the delivery chain, and how long they will have to wait for it to arrive.

The final customer transformation in the DAGMAR model is action. The action, as mentioned above in the advertising review, is the customer ultimately purchasing an item from the site. Only a thin line separates this stage from the conviction stage. Usually, once the customer is convinced, an action is immediate. This action may take the form of either trying a product sample, or buying the product. From the seller's point of view, of course, the purchase action is the more desirable action.

Selling is similar to advertising, but Internet sales raise two further issues:

Site usability is of paramount importance. Customers deserve, and will demand, high levels of support and easy access. Remember that customers can easily go elsewhere if a site is confusing or difficult to use. Issues concerned with user interface design were dealt with in Unit 3.