Use search techniques

Once you have a list of keywords, use search techniques to create your search strategy and search statement(s).

Common techniques for searching are:

These search techniques can be used across library search tools, databases and search engines. Check the Help screens of the search tool to understand which operators and syntax are valid.

Search operators

Most library catalogues, databases and search engines use standard search operators (also known as Boolean operators) to combine keywords. There are three common operators: AND, OR and NOT.

AND and OR are most commonly used.

The AND operator

The AND operator finds only records that include all the listed keywords. Use AND to combine your different concepts. This will narrow your search.

The OR operator

The OR operator finds records that include either keyword. Use OR to combine synonyms and alternative words and broaden your search.

The NOT operator

The NOT operator excludes words from a search. Use NOT with caution as you may accidentally exclude useful material.

Example use of search operators

Our example assignment topic

"Discuss how the development of artificial intelligence will impact University Libraries in the next 5 years."

Here are some examples of these search operators using our example keywords from our assignment topic:

(Artificial intelligence OR AI) finds records containing one or both words.

(University NOT college) ignores any record containing the second keyword.


Nesting is used to group synonyms and alternative words to control the order of the search and involves putting keywords and the relevant search operators within brackets.

A search statement is performed left to right (like a mathematical equation). If brackets () are used, the parts of the search contained within the brackets are performed first.

Without brackets, the operators are performed in an illogical order so the search will return irrelevant results.

For example: University Library AND (AI OR robotics) will return different results from University Library AND AI OR robotics.

Phrase searching, truncation and wildcards

A phrase search looks for two or more words next to each other exactly as typed.

Usually double quotation marks " " are required around the phrase. For example:"artificial intelligence" / "social media" / "university library".

Truncation uses a symbol (often the asterisk *) to find records that include any keyword starting with the word stem (the first few letters of the word). Use truncation to broaden your search by picking up plurals and word derivations.

Be careful where you place the truncation symbol. For example a search for rob* would pick up robotics and robots, but also robbery, robin, and robes. However, a search for robot* would pick up robot, robots and robotics.

A wildcard uses a symbol (often a question mark ?) to replace one unknown character in a word search. Use wildcards to pick up words that have different American and British spellings.

Keyword and subject searching

You can also choose to perform a keyword or subject search.

Keyword searching is the default search in most search tools and the best place to begin. It:

  • finds keywords anywhere in the record
  • is not precise if only a single keyword is used
  • is useful for discovering new terminology.

Subject searching involves searching only within the subject field of the record within a database. It:

  • only searches in the subject field of the record
  • is a more specific search and will retrieve fewer results
  • is useful for finding information on a topic regardless of the specific terminology.

Different search tools use different subject headings (also called subject terms, descriptors or index terms). General search tools such as Library Search have very broad subject headings, while those in specialist databases are more specific and detailed.

Keywords and subject headings can be combined using search operators.

Quick tip: Use subject headings to find other sources with the same headings and consider adding them to your search strategy as a new keyword as shown in Step 4 of the Information Searching Lifecycle (YouTube video, 2min).