The process of counting and auditing the clicks for a campaign. Click tracking can be done by a different entity than that which serves the creative.
Counting clicks on links via a redirected counter program that counts the clicks.
A report showing what parts of a web site a visitor looked at This information is gathered by keeping track of which links the visitor clicked on, or by looking in the web site's log files. Click tracking does not provide as much insight into a visitor's intent as the newer "Search Analytics" product do. (defined below)
Search engines can track user clicks in order to "learn" from users which pages are most relevant to a query. The best-known example is that of "Direct Hit", a discontinued search engine that not only tracked clicks but also logged the amount of time users spent on pages returned in order to improve relevance.
This is a search engine marketing term which denotes what number of users click a link on a results page, and how long their subsequent visit to the web site lasts for.