Words that must be in the document can often be indicated with a plus sign, and those to be excluded by a minus sign. For example, a search for anthropologist is interpreted as a search for anthropolog. Some search services interpret adjacent search terms starting with capital letters as proper names. Frequently it is a significant factor. Many search engines provide this feature.
Most search engines take some portion of the text to provide an abstract.
Dates are often useful. A number of search engines give the option of treating all pages from one site as one entry, a feature which is often useful. Index spamming Index spamming is the practice of inappropriately stacking Web pages with words likely to be used as search terms and hence to boost the chances of being found through a search and accessed. Index terms may be incorporated into the metadata in the head of the document or placed in an area of the document body not normally seen by the user. Some search engines have built-in safeguards against index spamming and may block offending sites.