In all the way to promote the network, the search engine is the most talked about, we will also start a promotion tour from here.
1, two of the most basic vocabulary: search engine (SearchEngine): by running a software, the software through the various links in the network, automatically get a lot of web page information, and classified according to certain rules, so as to form the database for query. Such a site (access to information ==> finishing the establishment of the database ==> query) we call it "search engine". The software used is generally called "Spider", "crawlers", etc.. Directory (classification): through the "manual" will be classified and set up the site to provide a database query, such a site called "classification directory". Typical search engines such as AltaVista, Excite, HotBot, Inktomi, etc., and the most important category is Yahoo.
in both "search engine" or "category", the target is the same: site data, database query. Just use different methods.
"search engine" because rely on software automatically, therefore, the capacity of the database is very large, but with the query results are not accurate; and the "Catalogue" by relying on artificial classification, query information should be accurate, but the contents of the collection is very limited.
we usually put the two class collectively referred to as the "search engine", in the discussion below we will be "automatic" search engines, as the "artificial" such as Yahoo, I will discuss separately in the "Chinese Yahoo".
2, the major search engines:
seven major search engines and the number of pages each include: engine AltaVistaNorthernLightInktomiExciteLycosInfoseekWebCrawler page number (million pages) 1501251105550452 (the above data for the February 1, 1999 Statistics)
The three step, 3 search engines work