Banner ad--or ad banner, also known as online ad, is a graphics image linked to an advertiser's website. The online ad industry has nine standard sizes for banner ads, but the most common is 468 pixels wide by 60 pixels tall, with a pixel being equivalent to one screen dot. In print ads, measurements are made by number of column centimeters.

Banner ad exchange program--trading or barter of banner ads among smaller websites. The Link Exchange Network is the most common of such programs.

CASIE--short for Coalition for Advertising Supported Information and Entertainment, an ad industry organization that promotes awareness of advertiser issues surrounding the Internet (www.casie.com).

Click rate--also called ad click rate or click-through rate, is the percentage of times an ad is clicked divided by the number of times it is served. If an ad is served 200 times and 10 visitors actually click on the ad, the banner has a click rate of 5 percent (10 divided by 200).

Click throughs--also known as ad clicks or transfers, is when a site visitor actually clicks on a banner ad and is transported to the site of the banner advertiser.

CPM--cost per thousand, the "M" stands for the Roman numeral for 1,000. It literally means the cost of 1,000 ad impressions. CPMs on different websites vary, depending on the quality of the advertiser and the target of the site's content.

Eyeballs--literally, the number of "eyes" which view a webpage, or the number of people who visit a site.

Hits--the number of files contained in a webpage which are successfully served to a visitor. If a webpage has six graphics images and one text file, and a visitor requests for that page, that would account for seven hits for the site. This term is no longer used for accurate measurement of a site's popularity. Page views are the more accepted metric.

HTML--a geeky term you don't wanna know in detail, but it forms the base language on which webpages are written.

Impression--also known as an ad view or exposure, occurs when an ad banner is served. If one page has four ads, that counts as four impressions.

IAB--Internet Advertising Bureau, an industry organization founded by Internet publishers that standardizes online advertising measurements (www.iab.net).

Link--also known as hyperlink, this is any text, button or graphics image that transports the visitor to another webpage once the link is clicked.

Page impression--a successful page request that displays the desired content in a user's browser.

Page request--data submitted to a server asking for specific content when a user clicks on a link. Not all page requests become page impressions since some users abort the download by clicking on the "stop" button or get impatient and move on to another site.

Page views--also known as page impression or simply an impression, is when a webpage is presented to a website visitor. Home pages generally get more page views than other pages in the site, which is why more advertisers place their banners on home pages.

Pixel--short for picture element. A pixel is the smallest element that display or print hardware and software can manipulate in creating letters, numbers or graphics.

Stickiness--a website's ability to attract visitors back to the site more frequently. Personal home pages, customizable interfaces and web-based e-mail services are examples of sticky services.

Unique visitor--also known as a unique session, is the net and unduplicated reach of a website over a certain period of time. An important metric for measuring website traffic, particularly in combination with page views. For example, total page views per month divided by unique visitors per month equals page views per unique visitor per month, an indicator of website stickiness.

Visitor--also known as a session or a user session, is the total number of people who access a website over a certain period of time. Unlike "unique visitors" which is a net number, a "visitor" is a gross number, meaning two "sessions" by a single user would count as two visitors.