Some search engines on the web use a default search of "OR." This means that when you type in a search statement such as--rapid prototyping--those search engines will return Web pages which contain any of those words (rapid or prototyping or both), often resulting in thousands of hits. By using quotation marks, you can indicate the words must be found together, in that order, on the page:

"rapid prototyping"

The Plus Sign + can be used in front of search words to indicate the search results must contain the word or phrase.

+"rapid prototyping"

If you want to exclude a word, use the Minus Sign - . Many words have multiple meanings and this can interfere with search result relevance. For example:

+spirits -alcohol

+bridge +cards -dental