Pay per click (PPC)
Internet advertising model used on websites, in which advertisers pay their host only when their ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system.
Cost per click (CPC)
Amount of money an advertiser pays search engines and other internet publishers for a single click on its advertisement per visitor.
Pay per Impression (PPI)
Often abbreviated to PPI or PPM for Pay per thousand impressions, is a phrase often used in online advertising and marketing related to web traffic. It is used for measuring the worth and cost of a specific e-marketing campaign. This technique is applied with web banners, text links, e-mail spam, and opt-in e-mail advertising, although opt-in e-mail advertising is more commonly charged on a cost per action (CPA) basis although sometimes CPM is used.
Similar to pay-per-click (PPC) advertising which is the dominant form of online advertising. In pay-per-call, however, the advertiser receives a phone call, a majority of current pay per call provider use web forms to generate phone calls. This type of advertisement is now very popular with Yellow Pages companies.