| Click-through-rate | The number of clicks on a link, as a percentage of the number of … |
| Cloaking | Cloaking is a method by which specific content is served up to the search … |
| Clustering | In search engine search results pages, clustering is limiting each represented website to one … |
| Content-rich Doorway | A doorway page dressed up with graphics, navigation, and linked to from a site … |
| Contextual Link Inventory | Contextual Link Inventory or CLI is text-link advertising that is displayed based on the … |
| Conversion rate | The key metric to evaluate the effectiveness of a conversion effort (accepting a free … |
| Cost-per-click | The amount an advertiser pays an ad host (such as a site owner, search … |
| Cost-per-thousand | A common term from traditional media advertising; online it refers to the cost per … |
| Crawl Page | A document consisting of links to other pages, provided for the sole purpose of … |