AND, OR and NOT are called Boolean operators.
They help connect your keywords/phrases together and narrow down your search.
In Library Search (and many databases), the AND, OR and NOT options are included within the advanced search screen. You can also type them into the basic search box.
Basic search screen:
Advanced search screen:
You can use brackets (parentheses) to clarify the order of precedence when you have used multiple operators. You can find out more on the next page, or learn more about grouping search terms from our search platform provider.
Searching with AND ensures that all search terms are present in your results. This is useful when you are searching for something specific, although in BCU Library Search, if you don't use any operators between words then it is assumed that you mean AND.
If you want to buy lunch at the deli and ask for "sandwich" you could get any filling (or worse, all of them)! To narrow your choice down, you would naturally use the AND operator when you ask for what you want.
sandwich AND cheese
Subject searching is no different. The more specific you are, the better results you will get.
diabetes AND obesity
small business AND tax
Some other search engines, like Google, automatically assume you are searching with AND. However, many library databases require you to specify how you want to search so it's good practice to use it.
There may be multiple ways of saying the keyword/phrase you want to search for. By using OR to include alternatives you may find more results. You may also want to combine multiple concepts/keywords into one search, to expand the remit of the results.
There are some words which generally mean the same thing:
adolescent OR teenager
Others are perhaps dialect/country based:
trousers OR pants
You may also want to combine some broader but related concepts this way, if you don't mind which of the concepts is included:
fantasy OR horror OR science fiction
If you are combining Boolean operators, there are some rules around order of precedence. Learn more about Boolean searching.
NOT is an operator which is used to exclude words from a search. You can force your search to ignore common results relating to your topic. If your search uses common words/names, then a NOT can help filter out things you don't need.
Using NOT is a bit like picking out a particular colour from a packet of sweets.
smarties NOT red
It allows you to be more specific with your subject search.
art nouveau NOT Rennie Mackintosh
primary NOT maths
property law NOT intellectual
Use NOT sparingly. If you suggest a common word to exclude, you may find your results become too limited and miss some important research.
NOT can sometimes be represented with a -. In Google the search Jaguar speed -animal will exclude all references to the speed of the animal Jaguar.