A single keyword search means: "I want everything that includes this keyword."
Linking keywords with AND narrows a search, provides context, and means: "I only want results that include both keywords."
methamphetamine AND epidemiology
Three or more keywords narrow the search to a very specific context:
alcoholism AND motivational interviewing AND randomized controlled trial
NOTE: Many of the search tools in this guide are Google Custom Search engines. With Google, linking terms with AND is not required. For example, a search for methadone epidemiology will be searched as methadone AND epidemiology.
Linking keywords with OR expands a search, and means:"I want results that include any of these keywords."
smokeless tobacco OR snuff OR chewing tobacco
TIP: It is a good idea to search with and without quotes to see how results differ.
"treatment options" - results will contain the exact phrase - but you may miss other potentially relevant sources.
treatment options - results will contain the terms treatment and options, but not necessarily together or in that order.
In Google to limit results by dates, separate them by two periods without any spaces.
The example below translates to: "I want articles on methamphetamine and epidemiology published between 2012 and 2017:"
methamphetamine epidemiology 2012..2017