How the search engine works

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Full-text Search Engine





in the Search engine classification section We mentioned the full text search engine from the site to extract information to build a Web database concept. The search engine's automatic information collection function is divided into two kinds.   One is a regular search, that is, every once in a while (such as Google is usually 28 days), search engine actively sent "spider" Program, a certain IP address range of Internet stations to retrieve, once found a new site, it will automatically extract the site's information and Web site to join their own database.


another is to submit a website search, that is, the site owner actively to the search engine to submit URLs, it within a certain period of time (2 days to several months) directed to your site sent the "spider" Program, scan your site and the relevant information into the database, in case the user inquiries.  As a result of the search engine indexing rules have changed a lot in recent years, unsolicited Web site does not guarantee your website access to the search engine database, so the best way is to get some external links, so that search engines have more opportunities to find you and automatically your site included.





when users search for information by keyword, search engine will be in the database search, if found with the user requirements of the content of the site, then use a special algorithm-usually according to the page of the keyword matching degree, the position/frequency, link quality, etc.-to calculate the relevance of each page and ranking level,  The links are then returned to the user in order, depending on the degree of relevance.





  





Directory Index





There are many differences in catalog indexing compared to Full-text search engines.





first, search engines belong to automatic Web site retrieval, while directory indexing relies entirely on manual operations.  After the user submits the site, the directory editor will personally visit your site and then decide whether to accept your site based on a set of criteria and even the editors ' subjective impressions.





Second, the search engine included the site, as long as the site itself does not violate the relevant rules, the general can log in successfully. Directory indexing is a much higher requirement for web sites, and sometimes it may not be successful even if you log on multiple times. Especially Yahoo! such as Super Index, login is more difficult. (Due to login Yahoo! is the most difficult, and it is business Network marketing battleground, so we will be in a special space to introduce the Yahoo Yahoo skills)





In addition, when you log in to a search engine, we generally do not have to consider the classification of the site, and the login directory index must be placed in the most appropriate directory (directory).





Finally, the search engine in the various sites of the information are automatically extracted from the user's web page, so the user's point of view, we have more autonomy, and the directory index requires the need to manually fill out the site information, but also have a variety of restrictions.   What's more, if the staff think you submitted the site's directory, website information is not appropriate, he can adjust it at any time, of course, will not discuss with you beforehand.





Directory index, as the name implies is to store the site in the corresponding directory, so the user in the query information, you can choose keyword Search, can also be sorted by category directory level. such as keyword search, return the results of the same as the search engine, but also according to the degree of information related to arrange the site, but there are more human factors.  If you are looking at a hierarchical directory, the ranking of the sites in a directory is determined by the order of the titles (with exceptions).





at present, search engine and catalog index have the tendency of merging and infiltration. Originally some pure full-text search engines now also provide directory search, such as Google to borrow the Open Directory directory to provide classification queries. As with Yahoo!, these old directory indexes expand the search by collaborating with search engines such as Google. In the default search mode, some directory-type search engines first return to their own directory matching sites, such as domestic Sohu, Sina, NetEase, etc., while others are the default Web search, such as Yahoo.