【正文】 pay each time a user clicks on their listing and is redirected to their website. They do not actually pay for the listing, but only when the listing is clicked on. This system allows advertising specialists to refine searches and gain information about their market. Under the Pay per click pricing system, advertisers pay for the right to be listed under a series of target rich words that direct relevant traffic to their website, and pay only when someone clicks on their listing which links directly to their website. CPC differs from CPV in that each click is paid for regardless of whether the user makes it to the target site. CPA (Cost Per Action) or (Cost Per Acquisition) advertising is performance based and is mon in the affiliate marketing sector of the business. In this payment scheme, the publisher takes all the risk of running the ad, and the advertiser pays only for the amount of users who plete a transaction, such as a purchase or 蘇州大學本科生畢業(yè)設計（論文） 25 signup. This is the best type of rate to pay for banner advertisements and the worst type of rate to charge. Similarly, CPL (Cost Per Lead) advertising is identical to CPA advertising and is based on the user pleting a form, registering for a newsletter or some other action that the merchant feels will lead to a sale. Also mon, CPO (Cost Per Order) advertising is based on each time an order is transacted. Cost per conversion Describes the cost of acquiring a customer, typically calculated by dividing the total cost of an ad campaign by the number of conversions. The definition of Conversion varies depending on the situation: it is sometimes considered to be a lead, a sale, or a purchase. CPE (Cost Per Engagement) is a form of Cost Per Action pricing first introduced in March 2021. Differing from costperimpression or costperclick models, a CPE model means advertising impressions are free and advertisers pay only when a user engages with their specific ad unit. Engagement is defined as a user interacting with an ad in any number of ways. Though, as seen above, the large majority of online advertising has a cost that is brought about by usage or interaction of an ad, there are a few other methods of advertising online that only require a one time payment. The Million Dollar Homepage is a very successful example of this. Visitors were able to pay $1 per pixel of advertising space and their advert would remain on the homepage for as long as the website exists with no extra costs. Floating ad: An ad which moves across the user39。s screen or floats above the content. 蘇州大學本科生畢業(yè)設計（論文） 26 Expanding ad: An ad which changes size and which may alter the contents of the webpage. Polite ad: A method by which a large ad will be downloaded in smaller pieces to minimize the disruption of the content being viewed Wallpaper ad: An ad which changes the background of the page being viewed. Trick banner: A banner ad that looks like a dialog box with buttons. It simulates an error message or an alert. Popup: A new window which opens in front of the current one, displaying an advertisement, or entire webpage. Popunder: Similar to a PopUp except that the window is loaded or sent behind the current window so that the user does not see it until they close one or more active windows. Video ad: similar to a banner ad, except that instead of a static or animated image, actual moving video clips are displayed. Map ad: text or graphics linked from, and appearing in or over, a location on an electronic map such as on Google Maps. Mobile ad: an SMS text or multimedia message sent to a cell phone. In addition, ads containing streaming video or streaming audio are being very popular with advertisers. Email advertising Legitimate Email advertising or Email marketing is often known as optin advertising to distinguish it from spam. Affiliate marketing 蘇州大學本科生畢業(yè)設計（論文） 27 Affiliate marketing was an invention by in 1994 and was excelled by when it launched its Affiliate Program, called Associate Program in 1996. The online retailer used its program to generate low cost brand exposure and provided at the same time small websites a way to earn some supplemental ine. Contextual advertising Many advertising works display graphical or textonly ads that correspond to the keywords of an Inter search or to the content of the page on which the ad is shown. These ads are believed to have a greater chance of attracting a user, because they tend to share a similar context as the user39。s search query. For example, a search query for flowers might return an advertisement for a florist39。s website. Another newer technique is embedding keyword hyperlinks in an article which are sponsored by an advertiser. When a user follows the link, they are sent to a sponsor39。s website. Behavioral targeting In addition to contextual targeting, online advertising can be targeted based on a user39。s past clickstream. For example, if a user is known to have recently visited a number of automotive shopping / parison sites based on clickstream analysis enabled by cookies stored on the user39。s puter, that user can then be served autorelated ads when they visit other, nonautomotive sites. Ads and malware There is also class of advertising methods which may be considered uhical and perhaps even illegal. These include external applications which alter system 蘇州大學本科生畢業(yè)設計（論文） 28 settings (such as a browser39。s home page), spawn popups, and insert advertisements into nonaffiliated webpages. Such applications are usually labeled as spyware or adware. They may mask their questionable activities by performing a simple service, such as displaying the weather or providing a search bar. Some programs are effectively trojans. These applications are monly designed so as to be difficult to re