For more precise searching, connect your keywords in a meaningful way using the words AND, OR, and NOT.
Think of these connecting words as a bridge between keywords or concepts which allows you to narrow or broaden your search.
Using AND narrows your search.
The more keywords you connect with AND, the fewer results you will retrieve. The database will need to find each of your keywords in the text in order to show it to you.
For example: "homeless youth" and education and "new york city"
Be careful not to add unnecessary words to AND searches. You might miss pertinent information. Sometimes the simpler the search, the better.
Using OR broadens your search.
Here we are less picky with what terms we want to retrieve. Using OR is also helpful when we are searching for a concept that is described equally well by more than one term.
For example: cars OR automobiles
environment AND (water OR lake* OR river* OR stream*)
Here the first search is asking for all information pertaining to cars or automobiles.
The second search is a little more detailed, but more precise.
Using NOT will narrow your search.
This type of search is good to use when you already know what you DO NOT want. Let's say you are doing a search on new cars but you are only interested in American made models.
For example: (cars OR automobiles) NOT Europe.