As a result, they provide a good overview of what's available on a particular topic. Excite also provides very good page summaries, so you have the opportunity to preview the information before actually visiting a page. One of the most comprehensive search engines on the Web, it indexes the full text of each document it has cataloged. This depth is particularly helpful in locating obscure or uncommon references. While the Web offers numerous other sites for searching information, these five provide a good starting point.
All search engines ask for a key word or phrase to be searched.
However, there are a number of ways to narrow your search for particular information. Some directories or indexes have a list of categories that can be selected, allowing the searcher to select more and more specific subcategories. Other times, specific techniques, such as in the example search for American History below, can retrieve a wider array of documents. All documents containing the words American or History or both are retrieved. By using OR, the search has been broaded to include all documents that refer to either American or History.