Boolean operators define the relationship between search terms.
diabetes AND children = articles about children with diabetes
diabetes OR children = articles about either diabetes or children
diabetes NOT children = articles about diabetes, but excludes articles mentioning children with diabetes
This diagram will show you how the Boolean operators limit or expand searches.
Image attribution: CC BY-SA 4.0 by Cecelia Vetter
For more help, watch this video on Using Boolean Operators:
Proximity searching is an advanced search strategy where you can search for multiple words near each other. It allows you to find where multiple search terms occur within a certain number of words from each other.
The proximity operators are composed of a letter (N or W) plus a number (to specify the number of words). The number cannot exceed 255.
The proximity operator is placed between the words that are to be searched:
Near Operator (N): N5 finds the words if they are a maximum of five words apart from one another, regardless of the order in which they appear. For example, type tax N5 reform to find results that have a maximum of five words between the beginning and ending terms, that would match tax reform as well as tax that has been submitted for reform.
Within Operator (W): W8 finds the words if they are within eight words of one another, in the order in which you entered them. For example, type tax W8 reform to find results that would match tax reform but would not match reform of income tax.
In addition, multiple terms can be used on either side of the operator. See the following examples:
Note: Boolean operators (AND, OR, NOT) are best entered in upper case to ensure they are treated as Boolean operators instead of literal words.
Adapted from EBSCO's How do I create a proximity search? documentation: