Caching
The process of storing pages, images, or other items on a local server or user's computer to speed up the items’ loading. When ads are cached, they are displayed but are not counted by ad servers. Thus, caching of ads can lead to undercounting of the number of impressions.

Campaign
A Campaign is a combination of Creatives (text, banners, etc.), Publisher specific links/tags, and Campaign Terms. Campaign Terms determine the acceptable ways to promote the Campaign, the Events upon occurrence of which you receive compensation and the compensation amount, among other things.

CAN-SPAM Act
Federal law that establishes requirements for those who send commercial email.

Click tracking
The process of counting and auditing number of clicks for a campaign.

Co-registration
Cooperative marketing technique through which consumers register to receive multiple offers via one integrated registration form.

Confirmed opt-in
In email marketing, a consumer who after initially requesting to receive commercial emails from a company/in a field, confirms the request by clicking on a link in an email received as a result of the initial request.

Contextual advertising
Ads served based a web page's content.

Conversion rate (CVR)
This is the percentage of visitors who take a desired action.

Cookie
Text file downloaded onto a visitor’s computer hard drive to store information about the visitor's actions in order to better customize her next visits. A cookie can be read only by the server in the domain that stored it.

CPA (Cost per Action or Acquisition)
Pricing model in which advertisers pay a fee based on direct results. Advertiser pays each time a visitor clicks on an ad and takes some sort of action, whether it is a lead or a sale.

CPC (Cost per Click)
Pricing model in which advertisers pay a fee based on the number of clicks on their advertisements.

CPL (Cost Per Lead)
A CPA pricing model that typically pays a fixed fee for the acquisition of a customer lead, such as a filled-out form, a free trial offer signup, or free download.

CPM (Cost-per-Thousand Impressions)
Pricing model in which advertisers pay a fee based for every 1,000 times the ad is shown (ad impressions).

Creative
Ad, such as banner, text link, buttons, email, pop up, etc.

CTA (Click-to-Action Rate)
The percentage of people who take action after clicking on an ad.

CTR (Click-through Rate)
Metrics used in measuring the effectiveness of an advertising creative. This is the percentage of people who click on an ad after seeing it, i.e. number of clicks divided by number of impressions multiplied by 100.