Parentheses group complex phrases. In most search engines all but the first word should be preceded by an operator or the search engine could interpret the words as a phrase. 

eg.  You want to find a listing of all of the national parks and are pretty sure that this would be found under the National Park Service.

• PHRASE SEARCHING is a feature you want in every search tools you
  choose. Requires your terms all to appear in exactly the order you enter them. 
• Enclose the phrase in double quotations " " 
              Example: "National Park Service" in Google.

Practice: Do your own phrase search in Google

eg.  Your search for the effects of television violence results in too many hits. The Boolean AND might help. 

• children AND television AND violence

eg.  You want to make sure you get as many hits as possible since you are looking for a job as a newly graduated engineer. The Boolean OR might help. OR allows you to have either one term or the other appear in the search results which will increase your hits. In this case, choose to "or" the terms jobs and careers since they are synonyms.

• Try Boolean OR will help: (jobs or careers) and engineering

eg.  Your search for biomedical engineering and cancer results in a lot of academic programs, but you want research reports. So you try to exclude documents containing " Department of". The Boolean AND NOT might help. 

• Try "biomedical engineering" AND cancer NOT "Department of" 

eg.  You are searching for information on feminism.  

• TRUNCATION permits retrieving all these variations in one search
  term: femini* matches feminine, feminist, feminism, etc.