On the other hand, your work plans, sales and marketing plans, management directives change on a daily basis. Also pay attention to how good relevant ranking is. Many search engines allow you to restrict web pages to within a certain periof of last modification dates. Category-based search is more subtle, because it requires web pages or documents be grouped according to some criteria and search be confinable to a certain subset of categories. The prerequisite to this question is that the search engine is able to index different document formats.
Partial search is very important for English.
Note that these features will inevitably requires large storage and more computational time. Translating a query is of course much simpler than translating a free text. Search speed is of course essential. However, insertion speed is equally important for Internet portals because each day there are thousands and thousands of new web pages to be inserted. For Internet and Intranet portals, you would welcome the pleasant surprise that usage is higher than what you expected.