It will also search for documents that are about the same concepts that your query describes, so sometimes it will bring back articles that don't mention any of the words in your original query. The most simple type of a query is made up of keywords. The search software will also search for documents that are about the same concepts that your query describes, so sometimes it will return articles that don't mention any of the words in your original query. On the other hand, it will do a pretty good job of figuring out what documents are interesting to you even if your query is vague. Several logical operators are available.
Parentheses are also available for logical grouping.
By mixing keywords and operators, the user can narrow down the search. These scores have no meaning outside of the relative relevance rankings of your search. Note that questions made up of natural language, relevant documents, and boolean expressions are all weighted using these techniques.