As many website owners rely on search engines to send traffic to their website, and entire industry has grown around the idea of optimizing Web content to improve your placement in search engine results. Learn more about search engine optimization (SEO) in this Webopedia' definition.
Local (or offline) Search Engine: Designed to be used for offline PC, CDROM or LAN searching usage.
Metasearch Engine: A search engine that queries other search engines and then combines the results that are received from all.
Blog Search Engine: A search engine for the blogosphere. Blog search engines only index and provide search results from blogs (Web logs).