Keywords are typically words/short phrases in natural language which describe what you want to search for. Think about how you might search Google:
When thinking about academic research, you will want to pick out key themes from your assignment title/essay plan/literature review outline. There are some useful writing guides which demonstrate how to do this. The words relating to these themes should form the basis of your keyword search.
Remember the rules of AND, OR and NOT. If you type Harry Potter into a search engine it will naturally search for Harry AND Potter - meaning you may find publications written by Harry Smith and John Potter, for example. You can use quotation marks to force a phrase search "Harry Potter" to narrow your results down. More on phrase searching below.
In contrast to keywords, subject headings represent a controlled vocabulary based on a subject area.
If a database uses subject headings then the results will be more accurate when these are used instead of keywords. It may also change the way you search. You will commonly see these on our health databases (e.g. CINAHL) which use the National Library of Medicine's Medical Subject Headings (MeSH).
Phrase searching is a way of making your search more specific via proximity.
Some search engines treat all words as a phrase, others automatically place AND in between words unless you use quotation marks or parentheses (brackets) around them to force a phrase.
(tulips in spring)
"tulips in spring"
tulips AND spring [see "stop words" to see why "in" wasn't included]
Using a databases "advanced" search option will usually perform this action for you. Otherwise, most databases contain a guide to explain how their Boolean connectors are used and how phrase searching is performed.
Stop words are the most common words which you'll find in each language. When you search for a stop word, most databases will ignore them during a basic keyword search.
These are just some the words ignored by Library Search:
If these words are crucial to the meaning of your search, you will need to use quotation marks " " to force the database/search engine to use them.
Here is a full list of stop words.
If you search for man of the year, Library Search will ignore the words "of" and "the", meaning it will find any publications mentioning both "man" AND "year".
If you search for "man of the year" with quotations, it will find that exact phrase, including "of" and "the" in that order.