Searching for information on the web

For most search engines a space is considered to be an or operator. If N2O emissions is entered as a search string the search will yield a list of all sites containing N2O or emissions or both N2O and emissions. Quotation marks can be used to narrow the search. If the phrase "N2O emissions" with quotation marks is entered the search will yield only sites containing that entire phrase. Similarly "nitrous oxide" would be clearer than nitrous oxide which would be interpreted as nitrous or oxide.

Attach a plus sign in front of words that must appear in the result documents.
Attach a minus sign in front of words that must not appear in the result documents.

Every search engine provides a help section. These sections provide valuable assistance in the design of searches.

Selective search engines http://www.yahoo.com/ http://www.looksmart.com/ http://www.ask.com/ http://dmoz.org/ http://www.webcrawler.com/ http://www.lycos.com/ http://www.snap.com/ http://www.go.com/

Comprehensive search engines http://www.altavista.com/ http://www.excite.com/ http://www.alltheweb.com/ http://www.hotbot.com/    Popularity search engines http://www.directhit.com/ http://www.google.com/

Description and list of search engines