Above the fold: The top part of a Web page that is visible without scrolling

Affiliate marketing: Using other online marketers as a source of referrals; payment is usually per click, per lead, or per sale.

Affiliate network: Third party that provides services, such as aggregation and tracking, for affiliates and marketers.

Banner ad: A graphic ad on a Web page, typically measuring 468 pixels wide and 60 pixels tall.

Blog: Online journal of entries in reverse chronological order that typically features multiple links; short for Web log.

Button ad: A graphic ad on a Web page that’s smaller than a banner

Click-through rate (CTR): Average number of click-throughs for an online ad per 100 ad impressions; a 2% click-through rate means for every 100 times the ad was seen, two people clicked on it.

Cookies: Files from a Website that are transferred to and stored on a visitor’s Website that provide information, such as what the visitor purchased and what site the visitor was on immediately preceding the visit, to the Website.

Contextual marketing: Placing merchandise near relevant content.

CPC: Cost per click

CPM: cost per 1,000 impressions.

Extranet: Group of Websites, each with a different owner, that joined together to share information; often used in supply chain management.

Frequency cap: Limit on the number of times a single viewer can be exposed to the same ad.

Impressions: The number of times a page is accessed or an ad displayed.

Interstitial: Online ad that loads between two content pages.

Intranet: Online network designed to be accessible only to members of a specific organization, with firewalls keeping out other potential users.

ISP: Internet service provider.

M-commerce: Mobile commerce; marketing via a mobile device such as a cell phone or a PDA; also called wireless commerce.

Pay per lead: Online ad payment model in which payment is based on the number of qualifying leads.

Pop-under ad: Ad that is displayed in a new browser window that appears under the already-open window.

Pop-up ad: Ad that is displayed in a new browser window.

Pay per sale: Online ad payment model in which commission based on each sale it generates, as opposed to each click or each lead; pay-per-sale programs have lower conversion rates than pay-per-click or pay-per-lead (as not every person who clicks ends up buying) pay higher commission rates.

Reciprocal links: Links between two Websites based on an agreement between the two owners.

Rich media: Web applications that offer a more interactive, animated online experience; examples including Flash and Shockwave.

ROS: Run of site; an ad that can appear anywhere in a given Website, rather than on one particular page.

RSS: Rich Site Summary or Real Simple Syndication; means of distributing dynamic content to subscribers via an XML (Extensible Markup Language) format rather than e-mail.

Shopping bots: Software programs that help Web users search for and compare specific products across multiple Websites; also called bots, intelligent agents.

Viral marketing: A campaign that uses word-of-mouth or “tell a friend” mechanisms.