Using a search engine is similar to searching the index of a book. The searcher enters a word and the engine retrieves records with keywords or phrases matching the term entered. Keyword searching can result in large unwieldy lists and terms are retrieved out of context. That's why it's good to know how to search effectively using boolean operators and truncation. Each search engine has its own rule for determining how sites are collected and arranged and how the search results are ranked according to relevance.
Search engines have different rules for entering search terms.
There are comparison charts available, or you can read the search engines help section. Also, view the search strategies section of this tutorial to find out some useful search tips. Links Search engine watch, a guide to search engines. How the 24 major search engines work. They are great starting points and are good if you are interested in searching within a topic.