it conveys information about how effective the advertising was. Clicks are a way to measure attention and interest. If the main purpose of an ad is to generate a click, or more specifically drive traffic to a destination, then pay-per-click is the preferred metric. The quality and placement of the advertisement will affect click through rates and the resulting total pay-per-click cost. Construction Cost-per-click (CPC) is calculated by dividing the advertising cost by the number of clicks generated by an advertisement. The basic formula is: Cost-per-click ($) = Advertising cost ($) / Ads clicked (#) There are two primary models for determining pay-per-click: flat-rate and bid-based. In both cases, the advertiser must consider the potential value of a click from a given source. This value is based on the type of individual the advertiser is expecting to receive as a visitor to their website, and what the advertiser can gain from that visit, which is usually short-term or long-term revenue. As with other forms of advertising, targeting is key, and factors that often play into PPC campaigns include the target's interest (often defined by a search term they have entered into a search engine or the content of a page that they are browsing), intent (e.g., to purchase or not), location (for geo targeting), device used (e.g. whether the user is searching from a desktop device or mobile) and the day and time that they are browsing. Flat-rate PPC In the flat-rate model, the advertiser and publisher agree upon a fixed amount that will be paid for each click. In many cases, the publisher has a rate card that lists the pay-per-click (PPC) within different areas of their website or network. These various amounts are often related to the content on pages, with content that generally attracts more valuable visitors having a higher cost per click than content that attracts less valuable visitors. However, in many cases, advertisers can negotiate lower rates, especially when committing to a long-term or high-value contract. The flat-rate model is particularly common to comparison shopping engines, which typically publish rate cards. However, these rates are sometimes minimal, and advertisers can pay more for greater visibility. These sites are usually neatly compartmentalized into product or service categories, allowing a high degree of targeting by advertisers. In many cases, the entire core content of these sites is paid ads. Bid-based PPC The advertiser signs a contract that