Click-through refers to a single instance of a user clicking on an advertising link or site listing and moving to a Landing Page. A higher Click-Through Rate (CTR) is one of the primary goals of Search Engine Optimization.
Click-Through Rate (CTR):
Click-through rate is the percentage of users who click on an advertising link or search engine site listing out of the total number of people who see it, i.e. four click-throughs out of ten views is a 40% CTR.
Cloaking is the presentation of alternative pages to a search engine Spider so that it will record different content for a URL than what a human browser would see. Cloaking is typically done to achieve a higher search engine position or to trick users into visiting a site. In such cases cloaking is considered to be Black Hat SEO and the offending URL could be Blacklisted. However, cloaking is sometimes used to deliver personalized content based on a browser's IP address and/or user-agent HTTP header. Such cloaking should only be practiced with a search engine's knowledge or it could be construed as black hat cloaking.
Contextual Link Inventory (CLI):
Search engines/advertising networks use their contextual link inventory to match keyword-relevant text-link advertising with site content. CLI is generated based on listings of website pages with content that the ad-server deems a relevant keyword match. Ad networks further refine CLI relevancy by monitoring the Click-Through Rate of the displayed ads.
Conversion is the term used for any significant action a user takes while visiting a site, i.e. making a purchase, requesting information, or registering for an account.
Conversion analytics is a branch of Analytics concerned specifically with conversion-related information from organic and paid search engine traffic, such as the keywords converts used in their queries, the type of conversion that resulted, landing page paths, search engine used, etc.