英语翻译
ween the time a site has been“spidered”and when it appears in a search index．Until this two-step process has been completed,a site remains unavailable to search queries．
Finally,the heart of each search engine is an algorithm that matches keyword queries against the information in the index,ranking results in the order the algorithm deems most relevant．
Because the spiders,resulting indexes,and search algorithms of each search engine differ,so do the search results and rankings across the various search engines．This explains why a top 10 site in HotBot may not appear near the top of Alta Vista when the same keyword search criterion is entered．
In addition,many,but not all,search utilities also reference metatags—invisible HTML tags within documents that describe their content—as a way to control how content is indexed．As a result,proper use of metatags throughout a site can also boost search engine ranking.