Proximity operators are used when a search is performed with two search terms that are not necessarily consecutive, but still at a certain distance from each other. A proximity operator is useful when searching for a term in a certain context, or when the search topic can be expressed with several similar phrases (e.g. energy policy, policy on energy). Proximity operators are database specific and not all databases use them. The functioning of the proximity operators must be checked in the database itself.
For example, near/3 in the ProQuest databases looks for references with search terms max. three words apart, in any order. Other proximity operators used in different databases: w/3, within 3, adj, sentence (terms are in the same sentence). Source: ProQuest <http://search.proquest.com> 10.7.2013.