Please refer to link popularity

Also known as 'impressions', this is a measure of the number of pages viewed by end users. It is a more accurate reflection of how popular a website is.

A technical asset of Google, it is an exponential-based value that signifies importance of a web page. Google allows one to view a site's PR [on an exponential 10-base] using their toolbar.

Short of Pay for Inclusion. Used by various search engines that guarantees that your site will be listed in a search engine database. Google is a note able exception that does not 'offer' such a service.

Please refer to ranking.

Un requested window that opens on top of the currently viewed window.

This is a generic term which refers to an entry website for a large population of users. This includes directories such as Yahoo! And search engines such as Google. In a more specific context, a portal is a website that is the leading authority on a specific subject.

Please refer to ranking.

'Search Engine' whose results are driven by PPC [paid per click] listings. Essentially all the search results are of CPC type.