AND OR NOT (also known as Boolean Operators or Boolean Logic) are three simple commands you can use to help obtain better results when you are searching the Internet or an online database They can be used to search for alternative terms, to combine concepts and to remove irrelevant terms. The terms should always be used in upper case.

In the diagrams below, the area in purple represents what is retrieved when you use the AND, OR , NOT commands. They demonstrate how you can broaden your search by using OR to retrieve more results and narrow your search by using AND, NOT to retrieve less results.

Example 1: Overweight OR Teenagers

Example 2: Overweight AND Teenagers

Example 3: Overweight NOT Teenagers

Most databases and search engines default to  AND. Check which command the database or search engine defaults to before you start to search.

Using truncation allows you to search for words with a common stem. This means you don't have to enter lots of different terms. This can be particularly useful for searching plurals. One of the most common symbols for truncation is an asterisk *, e.g. depress* for depressed and depression.

Enter the stem of the term you are looking for followed by the truncation symbol in the search box, e.g. searching for teen* will retrieve items containing: teen, teens, teenager, teenagers.

Be careful when using the truncation tool. If you truncate the word too much you will retrieve irrelevant results, e.g. cat* will retrieve cat, cats, catalogue, catastrophe.

Wildcards are similar to truncation. Using wildcards allows you to search for words that can be spelt in more than one way. As with truncations, one of the most common symbols for a wildcard is an asterisk*, e.g. colo*r for colour and color. In some databases a question mark '?' is used as wildcard.

Enter your search term and place the wildcard where the spelling variation occurs. For example:

• wom*n will retrieve woman and women.
• lab*r will retrieve labor and labour.
• an*esthesia will retrieve anesthesia and anaesthesia.

A phrase search is simply using inverted commas in order to search for words that appear together as a phrase. If you search for a phrase without using inverted commas you will retrieve items that contain both terms separately and therefore may not be relevant.

Example: search for items about chronic illness:

• chronic illness will retrieve any items containing the term chronic and the term illness.
• a search for “chronic illness” will only retrieve items where the terms appear side by side in a phrase.

Once you know how to use all the different tools for effective searching you need to be able to put them all together to create a search strategy.

Example: Search for items about chronic illness in overweight teenagers.

Your main concepts are: Chronic Illness, Overweight and Teenagers.

• For chronic illness: use the phrase search.
• For overweight: Search for obese as an alternative term using OR.
• For teenagers: Use the truncation tool to search for plurals.

=> “chronic illness” AND [overweight OR obese] AND teen*