Product Review – Search Engine Search engine can be categorized into 3 types based on the way index is built: Crawler Based Search Engine : search engine such as Google, Bing, Baidu etc, use a piece of software to “crawl” the web an then index what it finds to build the search base. Web changes can be automatically caught by crawler-based search engines and will affect how these web pages get listed in the search result. Crawler based search engines are good when you are looking for something very specific, say “Hong Kong Public Libraries”, but it is not good to search general topics, say “Search Engine”. A crawler based search engine can give thousands of irrelevant search result with many in which the key word appears only once. Human-powered Directory : Yahoo!, Open directory are popular search engines that depend on human editors to create their listing. Changes made to individual webpages will not affect how the website i...