Simply using AND, NOT, OR, or NEAR to combine keywords, a boolean search will only return search results to documents using those keywords, e.g. hotels AND New York, Invoice 57391 NOT Digital Copiers, Peanut OR Walnut, "Document Retrieval Software". The + and - signs can also be used in the place of AND or NOT respectively. Be selective on which words should be included or excluded from retrieval. Powerful leading search engines also use these types of searching. Hit words are highlighted and colour coded too.