Ad Server - Software that delivers and tracks advertisements independent of the web site where the ad is being displayed. Use of an ad server helps establish trust between an advertiser and publisher since the statistics are maintained by a objective third party.
CPA - Cost per action (CPA) is one of the online payment models by which advertisers pays for ever action (sale or registration) completed as a result of a visitor clicking on their advertisement. It is also used to describe the effective cost-per-acquisition that is ultimately achieved by other pricing methods. (For example an advertiser that paid a $1CPM for 100,000 impressions and received 10 signups effectively ended up paying a $10CPA.)
CPC - Cost per click (CPC) is one of the online payment models by which advertisers pays for each click through made on their advertisement.
CPM - Cost per thousand (CPM) is one of the online payment models by which advertisers pays for every 1000 impressions of their advertisement.
Click Through Rate - The percentage of impressions that resulted in a click through. Calculated by dividing the number of clicks by the number of impressions. For example if a banner was click on 15 times after being displayed 1000 times, the banner would have a click rate of ( 15 ÷ 1000 = .015 ) 1.5%.
Conversion - Term used to describe the process of getting a web visitor to accept an offer or become a paying customer. Advertisers strive for high conversion ratios.
eCPA - Effective Cost per Action (eCPA) is a term used to describe the effective CPA that an advertiser is receiving when running a CPM based campaign. (For example if an advertiser is paying a $2.00 CPM, and is getting a 1% click-through rate and a 0.5% conversion rate, they are effectively getting a $40 CPA.)
eCPM - Effective Cost per thousand (eCPM) is a term used to describe the effective CPM that a publisher is receiving when running a performance based campaign. (For example if a publisher is getting paid $10 per signup, but needs to deliver 100,000 impressions to get that signup, they are effectively getting a $0.10 CPM.)
Impressions - The number of times a banner ad was requested and presumably seen by users. It is often hard to obtain an accurate impression count as they can be undercounted due to issues relating to cache or overcounted due to requests that were not completed.
Inventory - The number of ad spaces available for sale on a web site during a certain time frame. Determined by taking into consideration the number of advertisements on a page, the number of pages with advertisements and the number of page views during a specific time frame.
Lead - Term used to describe a person or company that has expressed interest in an offer. Companies follow up on leads in hopes of converting them into customers.
Page View - Occurs when a users browser requests a web page. A single page view may create multiple hits to the server if the page contains multiple elements such as banners. Page views do not take into consideration users who may have their browsers set to disable images.
Unique Visitors - A term used to describe the total number of visitors to a site over a certain time period. Can be tracked by IP address in a log file or cookies, however due to mutiple IP usage and cookie deletion is not 100% accuarate. Occasionally tracked by number of visitors to login with a unique user name to gain access to a site.